The original vanilla Skyrim was pretty terrible. Don’t get me wrong it was playable but it was a very forgettable and unimpressive game. The low quality assets, the bugs, the half-assed talent trees, the uninspired and unfinished quest lines, the dumb AI, the barren ugly towns and landscapes etc. Just think about all the things you have to fix nowadays with mods to play it properly, nevermind adding new stuff.