3, 4 and New Vegas all performed well with the latter proving that you can mix it up drastically and still appeal to the original audience.
The fact that they keep mixing it up only proves one thing to me - that Bethesda haven't met their sales projections for the past games. Why else would you build games from the ground up? Larian haven't done that with Divinity: Original Sin, have they? It costs a lot more money to go back to the drawing board and come up with a new engine etc. Successful companies don't fix what isn't broken.
