Let me restate the original question in a different manner: I'm rated 1100, play 1.e4, don't like my results, and am considering switching to 1.d4: Is that the most likely option for improvement in my chess strength and results?
Stated that way, the answer is clearly and resoundingly NO.
The single activity most likely to improve the strength and results of an 1100-rated player is the examination and solving of realistic, game-situation-oriented tactic problems (in addition to playing serious games of chess, of course).
If at 1100, one wants to switch openings, who cares? Go ahead. I'll guarantee that you'll continue to drop pieces and miss threats and opportunities in games with the new opening as well; that is, until one's tactical prowess improves.
I've played just about every opening under the sun at one time or another. Give me 30-to-50 or so games in a new opening and I'm playing at my same strength: 1500. Why? Because my other skills (i.e., tactical vision and computation, endgame strength, planning, etc.) are still 1500 strength.
Openings (not general ideas about the opening, but specific openings and opening lines) are just about the least important part of chess for anyone 1400 and below. Any good teacher will tell you the same. But what do we obsess about most? Openings. If I could take 99% of the time I've spent on openings and have put it into tactics (and maybe a little more endgame skill), I'd be 1800+ rated, minimum. I have no doubt about it.
But still, if you feel like changing, change. You've got to have fun to remain motivated and if you're not having fun, do something different. I'd recommend (at least) 25 tactics problems a day, if I were your coach.
Best of luck,
DrawMaster
Learning how to play d4 can make all the difference!! I used to play e4 all the time when I was like 1000 but d4 can give you a very pleasant position. In fact, even at my level I usually get a two pawn or at least superior center! I recomend you add it to your repertoire and see how you like it. After 1 d4 d5, play 2 c4, and learn how to regain the pawn. The point is to play cxd5 and to follow up with a quick e4. If they play ...e6 or ...c6, play these moves: Nc3, Nf3, e3, Bd3, 0-0, and e4, which will probably give you a great position at your level. That's all you really need to know. It also avoids openings like the sicilian. Please try it.
I don't disagree that it's useful to be familiar with both e4 & d4. But is it really important or necessary for an 1100 player? I say no.