Do I need a Chess Opening?

I started taking my study of chess a little more seriously and have a daily schedule that I follow. It includes about a hour of opening study every Saturday - really not much out of a 7 day a week study schedule.In that hour of opening study I try to get general concepts of my choosen openings and have been using GM games to see plans and middlegame ideas.

I was playing a player this weekend who was rated slightly over 1600. I had white and opened with 1d4, something I never played but have seen a lot in the GM games that I have been playing through - so what the heck why not try it. I know about the first 5 moves, maybe.

After about 3 moves it was apparient that my oppenent was playing the Slav and seemed comfortable. Since I have never played d4 on my 6th move I must have been out of book - my opponent really look perplexed by my play, and struggled for about 2 mins before finding a move. We went for another 36 moves after which I held a nice pawn majority ending with two rooks against two miner pieces - but at last I ran out of time. It was GM 30.

I share all this because I was going to study the Dutch to use against d4 and the scandinavian to use against e4 - they seemed like the easiest of openings to learn and have for general play. But after seeing a 1600 struggle with the 6th move of a game I am starting to think meet e4 with e5 and d4 with d5 and save that hour every saturday for more end game or tactics study. 

It just does not seem like openings are of any importance - even at 1600 level. But I am affraid that I may be completely unprepared for some kind of trap especially for e4. I could use some advice by someone rated at least 1600 or higher.

Is it worth spending the one hour a week on those two simple openings or should I just stay with opening principles and spend that time elsewhere?
And what about as white?

Thanks

"... for those that want to be as good as they can be, they'll have to work hard.
Play opponents who are better than you … . Learn basic endgames. Create a simple opening repertoire (understanding the moves are far more important than memorizing them). Study tactics. And pick up tons of patterns. That’s the drumbeat of success. ..." - IM Jeremy Silman (December 27, 2018)
https://www.chess.com/article/view/little-things-that-help-your-game

"... As Black, I think that [players with very limited experience] would do well … playing 1...e5 versus 1 e4 and 1...d5 versus 1 d4. … [After 1 d4 d5, if] White plays the most important move, 2 c4, inexperienced players might want to begin classically with 2...e6 followed by ...Nf6 and ...Be7 …" - IM John Watson (2010)
"... Overall, I would advise most players to stick to a fairly limited range of openings, and not to worry about learning too much by heart. ..." - FM Steve Giddins (2008)
"... the average player only needs to know a limited amount about the openings he plays. Providing he understands the main aims of the opening, a few typical plans and a handful of basic variations, that is enough. ..." - FM Steve Giddins (2008)
"... Review each of your games, identifying opening (and other) mistakes with the goal of not repeatedly making the same mistake. ... It is especially critical not to continually fall into opening traps – or even lines that result in difficult positions ..." - NM Dan Heisman (2007)
https://web.archive.org/web/20140627062646/http://www.chesscafe.com/text/heisman81.pd

you have to remember that until you get to 1700-1800 and above level, alot of these low level players will have a couple openings for white and black and maybe a pet opening. however once out of opening people tend to play chess chess like a weaker player. A true good player can find the correct ideas in a position that they are not familiar with.

"... I feel that the main reasons to buy an opening book are to give a good overview of the opening, and to explain general plans and ideas. ..." - GM John Nunn (2006)

It's a good habit to have an opening repertoire at any level. The depth of analysis is the difference between the levels of play.  If you are under 1800 - try to have a really basic opening repertoire. Which doesn't mean that you can make random moves. Learn the general ideas of your opening and main lines. Pick up an opening which fits your style. All openings are hard to learn. Even books on London system are 600-page books. So... For instance I like to have a tactical positions, so I decided to play KID and French for Black, and aggressive lines of London system for White.

https://www.chess.com/forum/view/general/i-hate-opening-theory