I don't think it's accurate to lay the blame on a single cause. For me, and a lot of people I know, the gear upscale IS the primary issue, and I've gone from playing for several hours every day for years to essentially not playing at all.

I'm sure that for the "top tier" players who are able to clear content quickly (often with questionable methods), boredom and lack of content is a major problem, but to deny that SE's recent decisions have been disastrous as well is rather disingenuous. SE needs to work on pleasing both types of players, and I think that both issues can be sorted out by quite similar solutions. It would be more positive for us as a playerbase to stop arguing about what the problem is and start focusing on making SE fix all of it so that everyone can be happy.