You fell in love with a game and it's characters, sunk hundreds, maybe even thousands of hours into it. It became a comforting, immensely satisfying part of your daily life. Then you heard a sequel was coming and got really hyped but when it came out it was utter rubbish...
I think the rose tinted glasses effect is strong. Fallout 4 wasn’t that bad and had some neat characters and sidequests. I played heavily modded NV too, and while great, has plenty of missed beats and slow quests.
Also, making a (mostly) top down, tight text game is very different than producing a voice acted, sprawling 3D world. It’s like trying to compare the writing quality of a novel vs a 2 part blockbuster movie.
Not that I disagree with the decline, but I think that’s putting it too strong and ignoring huge differences.
For me the technical and artistic of aspects are factors too. Starfield would’ve been unreal if it came out in 2012… but look at its contemporaries. CP2077? KCD2? Even ME Andromeda utterly trounces it in artistic creativity, animation quality, graphics, scripting, performance, HDR quality, combat, even some voice acting; I could go on and on. And it’s basically the same premise.
Yet Starfield feels like modded Skyrim, looks only superficially better, and runs at like a tenth the speed.