Prettier graphics aren't a good replacement for lacking art. The world of Morrowind looked unique, majestic. Oblivion? Generic and boring.

Exploration was destroyed by lack of reward... don't even mention the extremely stupid "enemies level with you" system.

Conversations weren't too long in Morrowind, but the VO requirement made them even shorter, and less frequent in Oblivion. It was a pain.

Then there's the consolised inventory, "easier" made skills (read; a lot less), and far more mistakes.

Sequels should build on their predecessing game, not give less.