I think its just a trend in chess where different openings become popular in phases. Right now, it is sicilian(against e4). This will go on until another opening attains that following. And this following is attained generally because it is played in a famous game or a famous player. For example, sicilian najdorf seems to have gained its following due to its use by Kasparov.
Why do people like the silican so much?

Makes sense, One thing you said is the reason why the sicilian is so popular:
It's extremely hard to play against a sicilian to someone that isnt well versed in opening study, but it's pretty natural to play against 1.e5.
In class level the sicilian requires skills that players don't have until 1800's or so:
-To mount an refined attack against a structure that has no weaknesses to attack.
-Coordinate the defence on the queenside against black's powerful counterattack
-Play with a disavantage in the center
That's why so many people are attracted to the sicilian, it's much easier for white to make a mistake.
Actually it's pretty hard to white NOT to make a mistake in the sicilian.
O no you didn't!! You, my friend, just set yourself up for a slew of "Your rating isn't high enough for the Sicilian" "You do better with other openings" "You need to devote your time to basic principles until you are XXXX rating" etc. Fight the good fight comrade! Carry on.
An important reason the Sicilian is popular is that if black survives the middlegame, he often has the better position in the endgame.

Master Games in Chess Explorer might give you an idea:
When Black answers 1. e4 with 1...e5, white wins 37 percent of the time, 36 percent end in draws and black wins 27 percent of the time. When Black answers 1. e4 with 1...c5, white wins 37 percent of the time, 30 percent end in draws and black wins 33 percent of the time.

The sicilian where black plays 1...c5 following with 2..e6 is very tricky to deal with specially if he continues with 4...a6! These move order poses some problems for white’s king bishop!
Lol. It's not tricky to deal with.
I think its just a trend in chess where different openings become popular in phases. Right now, it is sicilian(against e4). This will go on until another opening attains that following. And this following is attained generally because it is played in a famous game or a famous player. For example, sicilian najdorf seems to have gained its following due to its use by Kasparov.
My not-very-authoritative impression is that Fischer had a lot to do with the rise of the Najdorf.
http://www.chessgames.com/player/robert_james_fischer.html
Anyway:
"As a professional player, I participate in many opens. I need at least 7.5/9 for the first place so I have little margin for mistakes. ... It suffices to mention the 6.Bg5-attack with forced variations all the way up to move thirty or more, to understand my reluctance to use the Najdorf. ..." - GM Alexander Delchev (2006)
"... I will try to predict the future course of developments in the theory of the Sicilian, over the near future. ... The more deeply we study [the position after 1 e4 c5 2 Nf3 d6 3 d4 cxd4 4 Nxd4], the more apparent White's advantage will become. The Polugaevsky Variation and the Dragon Variation will die out. The Paulsen and Najdorf Variations will survive longer, but they will face an unenviable fate: it will be hard for them to survive in the face of computer programs and multi-million game databases. ..." - GM Evgeny Sveshnikov (2014)
The November 2017 issue of Chess lists the top twenty openings compiled from a list of 2402 September games where both players were rated over 2400 Elo. One can not take position on this list too seriously because it is greatly influenced by how the openings are grouped. For example, all the Retis are grouped together, while English is separated into 1...c5, 1...e5, etc. Nevertheless, for what it is worth, some of the list entries are: 126 Retis, 100 King's Indians, 97 Nimzo-Indians, 84 Caro-Kanns, 76 declined Queen's Gambits, 73 Slavs, 63 Catalans, 61 Najdorf Sicilians, 58 1...c5 Englishes, 55 Berlin Lopezes, 55 Queen's Indians, 49 Guioco Pianos, 48 1...e5 Englishes, 45 Kan Sicilians, 43 1...Nf6 Englishes, and 42 Taimanov Sicilians.

I used to play the Caro-Kann for years. Found myself playing defense for the first 30 mves.
I finally got sick of it, and switched to the Sicilian.
Now I wonder why I didn't switch years earlier.
Another reason for the popularity of Sicilian is the wide choice for Black
The Sicilian Najdorf - most popular 1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6
The Sicilian Paulsen - very dodgy 1. e4 c5 2. Nf3 e6 3. d4 cxd4 4. Nxd4 Nc6 5. Nc3 Qc7
The Sicilian Lasker-Pelikan - original game 1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 e5

The sicilian where black plays 1...c5 following with 2..e6 is very tricky to deal with specially if he continues with 4...a6! These move order poses some problems for white’s king bishop!
Lol. It's not tricky to deal with.
It's the most tricky because white cant develop normally.

Makes sense, One thing you said is the reason why the sicilian is so popular:
It's extremely hard to play against a sicilian to someone that isnt well versed in opening study, but it's pretty natural to play against 1.e5.
In class level the sicilian requires skills that players don't have until 1800's or so:
-To mount an refined attack against a structure that has no weaknesses to attack.
-Coordinate the defence on the queenside against black's powerful counterattack
-Play with a disavantage in the center
That's why so many people are attracted to the sicilian, it's much easier for white to make a mistake.
Actually it's pretty hard to white NOT to make a mistake in the sicilian.
You are wrong in every single claim above, but this isn't something to distract you from your metaphysical chess studies.
I know what you are trying to say pfren, but if you look at some games of weaker players you will see horrible things, me included. It's not easy to play against certain openings when you are a weaker player. Sometimes natural moves can lose you the game or get you into a bad position.
If you just study a little opening theory just a tiny bit like 5-10 moves and then yourself + knowing some common plans you will be ahead of everybody on that level.

These moves happen a lot when white doesn't knwo the theory. They just see that they have to defend the pawn and do so by playing the natural Bd3 instead of the critical e5.
This is why I think that the sicilian is good at playing levels where the opponent aren't bad but doesn't know theory. This way you can equalize directly out of the opening and the rest is up to you.
The things master say about openings don't apply to us. If a master say this opening is a little bit better for white and white has to move pieces multiple time in the opening to achieve this you can be sure that your opponent will never ever play this move because nobody you play against will play a series of supertheoretical moves. They just don't know the moves or if they play these moves they won't be able to handle the upcoming positions. That's why most of the players play normal looking developing moves. which aren't bad but they don't pose any problems if you know a little bit about your opening.

People love to lose themselves in 500 years of opening theory?
The Sicilian and Ruy Lopez just might top the list?
Save yourselves some keystrokes, please.
Hard to answer.. I feel good when my 1. e4 as white is met by 1. e5 but I always go for 1. c5 as black against 1. e4. I must have some kind of dual-personality shit..

During paul morphy's time, king's gambit seems to be super popular. After that, its popularity waned. Sicilian was considered suspicious and inferior for a long time(from 1900 to 1950). Then, sicilian was revived in 1950s and sicilian dragon seems to have become really popular during Fischer era. Then, sicilian najdorf and paulsen became super popular with Kasparov. So, these are just phases. No opening is better or worse. The only thing is that an opening becomes popular and then it is deeply analyzed and most players get aquainted with that theory. This leads to diminishing returns at some stage. Then, players move on to another opening and this process repeats again.
Makes sense, One thing you said is the reason why the sicilian is so popular:
It's extremely hard to play against a sicilian to someone that isnt well versed in opening study, but it's pretty natural to play against 1.e5.
In class level the sicilian requires skills that players don't have until 1800's or so:
-To mount an refined attack against a structure that has no weaknesses to attack.
-Coordinate the defence on the queenside against black's powerful counterattack
-Play with a disavantage in the center
That's why so many people are attracted to the sicilian, it's much easier for white to make a mistake.
Actually it's pretty hard to white NOT to make a mistake in the sicilian.
You are wrong in every single claim above, but this isn't something to distract you from your metaphysical chess studies.