Fallout and Fallout 2 are two of my favorite games of all-time. I'd rank the Fallouts (that I have played):
1. Fallout 2
2. Fallout
3. Fallout New Vegas
4. Fallout 3
5. Fallout 4
I finished the rest of the games and they are all among my favorite of all-time... except for Fallout 4. I have tried to play Fallout 4 about five times and I can just never get into it, even though I want to. I find the characters to be bland, the settlement building to be a joke and the locations to be uninspiring. With the disaster that was Fallout 76 I just honestly don't think Bethesda gets what Fallout is or was meant to be. Fallout and Fallout 2 were about places that were rebuilding after the nuclear fallout. They were trying to clean things up, make things better, etc. They were trying to return to some semblance of normalcy...
Not just wallowing around in filth and destruction constantly - which is how Bethesda seems to repeatedly depict the universe.
I don't disagree with your opinion of character blandness. Bethesda's writing is definitelly well below what was done by Interplay/Black Isle and then later by Obsidian with NV. I do disagree about Bethesda's depiction being all about filth and destruction.
I do feel there is a lot of bias amongst fans of the older games though. I'm saying this as one of those older fans too BTW.
Project Purity from Fallout 3 is all about rebuilding and hoping for a better future. The main plot is all about hope for a better future and rebuilding. The BoS were the nicest they ever been too, in fact the game was heavily criticized for the BoS not being zealots willing to stomp on anything they considered wrong and actually being concerned with helping everyone for once.
Fallout 4's main plot isn't about rebuilding but the minutemen are all about that. So is the institute in their own twisted ways. The BoS are back to their old ways. Meanwhile Diamond City, the game's biggest city, is also all about rebuilding civilization with all of it's typical government and bureaucratic pitfalls
Fallout: NV had it's fair share of destructive forces too. Caesar's legion is nothing but filth and destruction. New Vegas, while certainly a beacon of civilization, is just a monument to filth and destructive/exploitative capitalism.
Fallout 1 and 2 had similar strokes too. Their main plot start off as just survival and then uncovering a bigger plot behind it all. Through all of it meeting factions/cities that are all about rebuilding and some that are all about destruction.
Don't get me wrong, FO1/2/NV have the superior plots, writing and, in many ways, are far superior games but I do feel like saying Bethesda's depiction of the world is too filthy and destructive is completely wrong. Hell, there are times when it feels a little too hopeful and easy to get by in Bethesda's wasteland.
FO76 was an experiment to bring MP to the series. I'm not sure if it failed. They're still supporting the game and updating regularly from what I've heard. I've tried it once and it definitely wasn't for me. I like my Fallout experience to be solo and not about MMO style fetch/destruction quests. Regardless of it's commercial failure or success, I doubt they'll try that again with the next game.
EDIT: all this talk of Fallout makes me want to replay them all... again. Damnit.