Roger Waters has stated in several interviews that the last time the band was actually working like a band was when they were making their ninth studio album, Wish You Were Here (and even then only in creating Shine On You Crazy Diamond as the other tracks were almost entirely written by Waters).
After that, it was pretty much “band-plays-music-that-Waters-wrote-with-some-input-here-and-there” until he left the band in 1985. Despite everything else, Waters was quoted as saying that that was the biggest reason why he left. At that point, The Final Cut might as well have been a solo album and it really wouldn’t have made any difference (he offered to release it as such but the label wouldn’t let him).
A Momentary Lapse of Reason was the band’s way of seeing if they could actually make an album without any input from Waters. I don’t know about you but the album sounds terrible aside from the instrumentals. Still, it was a hit worldwide (mostly because people would buy anything released by Pink Floyd at the time) and at the very least showed that they could make an album without Waters. The Division Bell was David Gilmour’s way of taking what existed in a raw form in AMLoR and combining it with the directed musical style of the older days (a central theme of communication with Waters as an overlying metaphor) to create what honestly might as well be the first Pink Floyd record without Waters on it.
Now what if Waters was less controlling? Gilmour once said that their worst album was Atom Heart Mother because they were “scraping the bottom of the barrel” in terms of creative drive. The same can be said for Animals or The Wall or The Final Cut — the band just didn’t have anything except in concentrated bursts of which we mostly don’t get to hear (case in point Dogs and Comfortably Numb, both of which had the most music written by Gilmour in an otherwise Waters-dominated album). If every member was contributing exactly 25% post-WYWH, I think we’d actually have a lot more album that sounds like AMLoR because it took Gilmour a long time to actually find his own sound (and, no, “his own sound” doesn’t include talking into a microphone for a minute and a half with no music at all). It’d be interesting to see what Richard Wright would have come up with post-1978 but that’s just what it is — interesting as opposed to desirable.
It wasn’t that Waters was taking control of the band, it was more like the band relinquished control to him because he was the only one with any sort of focused idea at the time. Did that eventually lead to the band’s collapse? Hell, yeah. Could it have happened any other way? No, I don’t think so. The band was doomed to fail the moment WYWH was released. So in a way, I actually kind of agreed with Waters when he said that Pink Floyd was a “spent force”. If you looked at the band in 1980 and took out Waters, there really wasn’t a band at all. At least no more of a band than Waters’ backup artists for his solo stuff. This is even further demonstrated when you consider how similar The Final Cut and Amused to Death sound even though one was Pink Floyd and the other was “Roger-Waters-and-the-musicians-he-scraped-together-to-perform-with-him”.