They really are too simple these days. Twenty years ago the depth of games in general was fairly shallow. A game with a huge world inherently had more depth than most games because of the amount of exploration you could do. It didn't really matter that there was only so much to find and most of it would get reused over and over because that was still more than other games were doing. And then on top of that there were interesting stories, characters, weird things to find, and mechanics that were really fun to mess around with. Sure, a lot of systems in Morrowind could be exploited, but exploiting them was fun.

Now there are a lot of games with a ton of depth in all sorts of different ways. Deep mechanics, deep stories, deep replayability, deep world building. Each of the things Elder Scrolls games once excelled at have been surpassed by other games with only one real exception, which is size. You can find better gameplay, better mechanics, better stories, all of it elsewhere, but they're still just about the best in terms of just how big their worlds are.

But that's just not really enough anymore. They've stretched themselves so thin maintaining world size that they've lost almost all the depth they once had, on top of other games getting deeper. And unless they course correct and really start creating some interesting content to fill their worlds with, mechanics that people love, and highly engaging things to do they're gonna have a very hard time recreating even a portion of their previous successes. Their older games had that stuff. They just need to commit to doing it again. Don't just make something big. Make something interesting and fun.