Without Gilmour, PF would never have been as successful or prolific. He isn't just "guitar player #4." When people listen to Time, Comfortably Numb, Echoes, Money, Dogs, Cigar, they don't remember that wickedly intense 4/4 bass line comprised of root notes, they connect with the phrasing and tone of the guitar solos. Gilmour's soundscaping inspiried countless hundreds of bands to push music into the next realm compared to where it was at the time.
There is no denying that Waters was important in the equation. While lyrically PF albums have never been that inspiring as a whole, he managed to pen some pretty fucking powerful lyrics here and there and he deserves respect for that, no question. His arrangements are also worthy of praise as the whole concept album genre basically started with his help.
The best anyone can tell, Gilmour decided he'd had enough of Waters' crying recorded on tape and felt that it wasn't in the band's best interest to release The Final Cut with the dedication to his father. Waters became petty and requested Gilmour's name be removed from the album as a producer. Waters then went on to petition that the name Pink Floyd not be used by anyone and even went as far as to try and get released from his contracts citing breach of contract because no new albums were being made. For the years after the rest of the band toured and recorded without him (another vote for the Waters is the real 'enemy' here) Waters would publically make slights towards his former band mates. PF would continue on and make substandard music for the most part. Waters presence was definitely missed but his ego surely wasn't.
Point being from all of this, PF only worked as a complete band. If you listen to Gilmour's solo efforts, the talent is clearly there and that is why the other members stuck with him. I do not blame Gilmour in the slightest for not wanting to be part of a cash grab like this. I certainly wouldn't. If Waters thinks that he can somehow change what the Wall was originally about into some limp dicked anti-war thing, more power to him. The war sentiment is clearly in the original recording but I feel it more a basis for the protagonist's isolationism than a war statement. The quote now on Waters' home page about why he felt it was time to bring 'The Wall' back has literally nothing to do with the original intent.
I disagree with your assessment of DG's guitar playing skills and influence 5000%. Of the instruments, only Wright created a unique style. Mason was a complete hack, and there are 91782649827348274872 David Gilmours in high schools all over the world. There is nothing about his playing that I find the least bit interesting, imaginative, unique, or impressive. I have About Face. It's godawful in every conceivable way. I would rather listen to water buffalo fuck than David Gilmour sing.
I agree almost 100% with your assessment of the band as a whole music group was brilliant and as anything else, unremarkable at best.
I disagree completely with your take on the personal situation with the band members and who was at fault for the demise of PF, or at least who was the biggest douche in the situation.
At the time of The Wall and The Final Cut, the "band" was only David and Roger. Wright was out, and if not for Roger, Mason would have been out too. They scrapped and fought about the recording more so than any others, but they always scrapped about the recording. In the end they got The Wall done and toured it. FC was cutting room stuff for The Wall. David didn't want to even bother with it. Roger knew it and wanted it to be PF's last album. The band broke up due to numerous factors none of which are Gilmour "had enough of Waters' crying recorded on tape". Let's try financial Armageddon, cocaine, cheating wives, and a long and tiresome career in the rock and roll industry, which kills most bands far more quickly.
The trouble with Waters' image really started years later after Gilmour and Mason wanted to tour as PF. To Roger, PF was dead. Anybody who has listened to MLoR and DB can tell you he was right. Was he really so wrong to want it to stay that way? Mason and Gilmour were only in it for the cha ching. Wright was only invited to make their legal case stronger. How is it the only guy with enough integrity to leave PF dead gets the blame? Even Mason has said publicly that Roger was right about the whole MLoR fiasco.
He made public sleights? The rest of the band were essentially laughing in his face and collecting money while they did it. Wouldn't you say something? Yep, he did everything in his power to stop M/G from touring or recording as PF and most of it was under legal advice. Unfortunately, he lost.
Saucer Full of Secrets