All valid reasons but I'd like to think it's people being smart with their money and time -- we have annual passes here and when we go to Animal Kingdom, never fail to run into a group that has dropped a significant amount of cash for vacation pondering whether or not it's worth the 3-5 hour wait (STILL) for the Pandora banshee ride.
Fast passes work great, but it's over a year later and you still never see passes for that ride pop up. Anecdotally, if Disneyland is anything like Disneyworld...I'd imagine attendance overall has increased significantly over the past 3-4 years. Spaceship Earth and the Viking ride (before the Frozen makeover) were practically dead for a decade prior to that -- you could walk on whenever you wanted and never wait more than 5 minutes. I can't think of a single ride at any of the parks where that applies these days -- possibly Figment?
Figment was about a 30-45 minute wait when I was there last summer. I honestly can't think of anything that took less than a half hour. Maybe Buzz Lightyear had we not wasted a fast pass on it (my dad wanted to make sure we got on it)?