One of my favourites too I always buy the new albums and enjoy them. Like you say, it's never going to be the same but I'm OK with that. Still excellent in my book and have seen them live a few times now.IMO the singer is the key to this argument. If a band loses it's singer then i feel they should disband. One of my favourite bands are Alice In Chains and they have replaced their singer Layne Staley who died many years ago now. They have released about 4 albums with a new vocalist and whilst they aren't bad, it's not the same and never can be. A drummer or another musician can be replaced in a band but the sound of the original singer cannot be replicated.
It helped that when AC/DC did it they released an absolute belter of an album.
I saw a video of the last Fleetwood Mac tour without Lindsay Buckingham and it just doesn't sound right to me even though he was replaced by two excellent musicians in their own right.
Every band has their own stories. Deaths, feuds, fall-outs, divorces to pay for (eh, Mick Fleetwood?). Seems harsh on those left behind to have to stop too. We can all choose whether to listen or not. It's their band and songs and their choice whether they wish to continue.