Regarding capacity - agree that there is a bit of a Catch-22 here. If Disney built 10 more Carousel of Progress / People Mover / Alien Saucer type rides, people would complain and it would be wasted money (those rides are already relatively low waits, after all, but that doesn't make them that much more attractive to guests). If they built 10 more Guardians of the Galaxy, they could well end up drawing in that many more people and it wouldn't do anything for capacity.
Maybe there is a sweet spot for "people eater" type rides - not too good, but not too boring either (Barnstormer level, maybe?) And certainly they could invest in other people eaters - street entertainment, shows, parades, etc. (In a way I'm surprised they're not building character dining as fast as they can - given how hard it is to secure ADRs, these places must be filling up, and each new restaurant brings in revenue).