I think my first Bethesda game was Skyrim and I love Skyrim. I’ve played through Skyrim when it first came out I played through it again in the DLC came out. I played through it again on the switch I have since played through it again on PC. I love Skyrim. I played it so many times and I know it’s a meme to keep re-releasing the game but it is just genuinely very good game.
I’ve played fallout three I tried to get into new Vegas. I played fallout four up to like level 40 just today actually and I’ve tried fallout 76. I know the gameplay is almost the same as the Skyrim game but I just can’t get into fallout and I don’t know what it is about that series . Maybe you can help me figure it out because I just don’t think this game is captivating.
It seems like there’s just less to do in the world enemies are Raiders or mutants and maybe some creatures and I guess sky rooms really the same it’s just different factions of humans but it just seems less copy and pasted than fallout does and of course Skyrim has the same dungeons, but so does fallout.
Is it just the genre of playing in a wasteland instead of a fantasy world the only real difference between the elder scrolls games in the fallout games? 
Side note, fuck am I old. 🥲 My first Bethesda games were Where's Waldo, Terminator and then a bit later Elder Scrolls: Arena. It was always sad to see how far the concept had actually fallen von the lofty heights of the Arena->Daggerfall jump and what it promised. Morrowind felt like a big reduction in scope but in return added a lot, so it felt okay. Then came Oblivion and that solidified the route that led to Skyrim and most post-Skyrim open world designs.
I think what you're feeling might just be... open-world realization? The fact that open games are naturally less engaging? The whole "Wide as an ocean, deep as a puddle"-thing?