I've thought about this a lot, and I think that most of us in the "pro" camp will come to enjoy the new style of trips quite a lot.
Why? It's based on my experiences over the last year or so at WDW, DLR, and DLRP---all of which enforced return times for Fastpass windows as of my most recent trips. That enforcement already changed the game, because now I don't go back for my mid-day break with a pocket full of e-ticket FPs to use at all of the attractions that night. That already means fewer re-rides on the headliners, and we found that we ended up using that time to see "lesser" attractions instead, and often things we never would have time to get to in our pre-enforcement days.
Guess what? We found that those "lesser" attractions were also really quite a lot of fun. In fact, it seemed to us that doing a wider variety of different things over the course of the day made the day better, not worse. My guess is that most people will find something similar in their future trips.
Will everyone? Probably not, and Disney will lose a few of those folks. But, on balance, leveling the playing field seems like it's going to work out very well for Disney. If that does, that will in turn justify even more investment in the theme parks, and that's going to be a good thing for those of us who continue to visit.