To your first point I will say there are posters who I have never seen post a single positive thing about Disney. Not a single positive.
I am sure there are some, and some of the very prolific posters of late do post much negativity. Even a few who keep making the SAME points over and over. They are the Dandelion posters. Some in the past were even booted. (and a few are reborn after being banned!)
But I also see you are new.
I think Tony67 made some excellent posts. I don't always agree with Minnie Mum, but she's been around a long time. She's had plenty of positive things to say about WDW, as have I.
Many of the folks who have complained about certain changes, have also posted in plenty of "Things I wish Disney WOULD change" threads, I know because all us long timers have posted in many of those threads and dream of seeing Star Tours type revisions to a number of shows. Especially nice would be having an attraction like Muppets with multiple versions instead of one. Keep the old, but add five new Muppets episodes into the mix.
It's funny, because whenever I post about a change I don't like, I get accused of hating all change. Often enough, those threads about changes we want- get debated by folks who happen to like the those same rides/shows. (well, except Stitch, that one pretty universally gets panned.)
Same thing with dining. Every place shows up on BEST place and Worst place to dine threads...and every month on BEST/Worst times of year to visit WDW.
So I go back to Tony67. I had big hopes for FP when it was first announced. I said early, they are likely going towards all FP-all-the-time system. I said it could be pretty neat- if done well- but would mean major rethinking of how we tour.
Well, the rollout hasn't been that smooth.
Another HUGE factor on the DIS is the economy, and general anxiety. When people feel anxious, they post negative. When their lives are good, their outlook on life improves, including attitudes about non-related things like WDW.