I’ve always been very disappointed about that. Gilmour’s not only a top-notch guitarist but also has one of the best voices in rock, past or present, IMO. If it were Roger Waters singing on all the tracks, I would definitely not like Pink Floyd nearly as much.
Personally I agree with Roger, though. There are a zillion guys who can sing and play as good or almost as good as anyone else. A great song is much much rarer.
Well, okay. Gilmour’s solo projects and Floyd without Waters don’t do much for me.
Still, Gllmour is the source of more than half of the enjoyment I get from Breathe, Young Lust and so many more tracks.
On the other hand, you can have a great song performed by competent, but uninspiring performers, and it’s not going anywhere. Until you get that performance that crystalizes the definitive version of the song, all of the good singers don’t know who to emulate.
As far as my own bands go, it’s always been verbally agreed at some point that if someone leaves or is ejected without the permission to continue the same band with a replacement, that band’s done. Get a new name and start again. So if you really hated that member, it better be worth starting again if you’re wanting to eject them without some sort of amicable agreement.
Then again, we never have worked at a substantial profit, so it was a gentleperson’s agreement in every way. I’m sure if there was worthwhile money at stake, there’d be lawyers recruited.
Rock critic Dave Marsh, while tracing the roots of the classic Louie Louie, ran across the reason the Kingsmen, who were basically a group of high school buddies, broke up. Only one member of the band had actually signed the papers registering the band’s name. He then decided he wanted to make changes (including making himself lead singer) and when other band members objected, he told he owned the band’s name, and they could walk away if they didn’t like it.
At one point in the band’s existence, Randy Owen wanted to change the band’s name to Randy Owen and Alabama. It caused some hard feelings.
Randy Owen read too many fan letters. 
Alabama’s vocal harmony were very, very good. I still love that band.