As @LeGardePourpre and @ncisGibbs02 have already mentioned, the more features get moved the basegame, the higher the chance that one of them is a dealbreaker. If I feel I absolutely need the, for example, the Seasons EP, because without it the basegame weather system is annoying, then I'd rather not buy the basegame in the first place.
A feature that probably needs to be made basegame even so is the club system. Student Societies and werewolf packs were very underwhelming, because they had to invent them again from scratch everytime anew.
