1. e3

So why is this totally dismissed?

if youre going to follow up with d4 then why not do so from the beginning. claim the center and dont waste time. if you like a pawn at e3 than start with a hungarian or work on an orangatang and play e3 later

It takes away a lot of lines that involve Bf4, Bg5, and even g3, so it is very unflexible. It is alright if in a sense you transposes to a viable opening such as the english or colle system, but I see no particular use other than transposition. It simply does not pack the punch or more mainline openings, usually giving black a very a easy game.

I used it once before because I wanted to play the bird's opening (1.f4), but not against from's gambit (1.f4 e5), and I didn't mind playing an e5 english with e3 (1. c4 e5 2. e3). My problem was solved with 1.e3 i.e. 1. e3 d5 2. f4 and 1. e3 e5 2. c4 which I enjoyed for awhile.

However, just keep in mind that black has a big variety of viable set-ups which lead to an equal game. So yes, 1. e3 can be a helpful transpositional tool, but I don't particularly recommend it if you're just try to be "original" or do something "different".

A friend of mine used to play 1. e3 a lot, his reason being that the pawn is less vulnerable than after 1. e4.  However, I don't think that that's sufficient justification, since 1. e3 simply does too little to control the center.

The reason is that white has at least 5 other first moves which are better: 1.e4, d4, c4, f4, Nf3.

1.e3 does not occupy the center and does less to control the center than any of the 5 moves listed above. It causes no trouble for black - black is now free to take over the center as he pleases.

If white has at least 5 other moves which are clearly better, why would he settle for an inferior move?

It's the Van 't Kruijs Opening (Van 't Kruys), a chess opening defined by the move 1. e3.  It releases the king's bishop, and makes a modest claim of the centre, but the move is somewhat passive.  The queen's bishop's development is somewhat hindered by the pawn on e3, and White usually wants to take more than a modest stake of the centre.  Although not very aggressive for a first move, play may transpose to lines of the English Opening (c4), Queen's Pawn Game (d4), or reversed French Defence (delayed d4) or reversed Dutch Defence (f4) positions.  Its ability to transpose into many different openings explains its attraction for some people such as the Czech Grandmaster Pavel Blatny, Aron Nimzowitsch and Bent Larsen.  Garry Kasparov has used the move against the Fritz chess-engine to get it "out of book."