Personally, I don't favor 3D and a lot of friends feel the same way, but it is definitely popular with the masses (much the same way a lot of cheesy things in life are popular). It has gotten people back to the movie theaters instead of waiting for NetFlix. Imax is popular too, but I feel it's just too much screen for me. I prefer my movies regularly projected (non digital) in 2D on the regular movie-sized screens. That's big enough for me. Even the most mediocre movie is like Christmas to me, but I don't enjoy the recent formatting gimmicks at all. I do like that it's helped the troubled theatrical film industry.
That's the problem. I have to admit, I do like seeing the animated movies in 3-D, and some of the animated movies basically add pointless stuff specifically to make the film a 3-D film. Despicable Me had a LOT of gimmicks that weren't all that integral to the plot just so people would pay extra to see it that way... and if you see it regularly, it just comes off as tedious. The Rollercoaster sequence and the end with the minions playing around. That's basically made for 3-D.
A Good movie (I liked Despicable, don't get me wrong) uses 3-D to ice the cake, and doesn't leave out the paying customers that DON'T want or care about the cheesy gimmicks. Both times Pixar released films in 3-D, it just added to the overall look. I saw Up in both dimensional options, and it didn't add or detract from the story or the film.
That said, 3-D's basically the ONLY thing keeping people in the seats. It's cheaper and easier to get a scratched up netflix or Redbox rental and see it on a crummy TV than to actually go to the theaters and experiance the movie. Not to mention people with WAAAAAAY too much money (or waaay too much credit card debt) that get those expensive home entertainment systems. The 3-D TV gimmick is still in its infacny, so it's the one thing movies still have over that.
Of course, it wouldn't hurt to NOT make a billion talking dog movies and pointless remakes of things that were pointless to begin with every year. And the price increase is crap. All Avatar's fault.