That is a great question! I’ve certainly asked myself the same thing and the only answer I can come up with in 2 parts.
1: The game is compulsive. While you are playing you want to keep playing. And while the moment to moment interactions are dull (imo) but not so dull as to drive me away. There may be plenty of Oblivion nostalgia keeping me playing.
2: Many of the games problems appear in retrospect. The dumbing down of the subsystems, for example. Much like Outer Worlds; it feels fine while you’re in there but once you stop and step back you realise how crappy they are.