Just wondering what you guys think on the subject.

Werewolves have appeared in 3 TES entries of 5 excluding Battlespire and Redguard.
I already consider them a moderate staple as they're tied to one if the Daedra Lord.

Yes, werewolves were in two of the previous numbered entries, Daggerfall and Morrowind's Bloodmoon expansion, so they've been kind of a staple for a long time now. Vampires have been in the series since day one with Arena, but Daggerfall was the first entry to allow the player to become one.

they have appeared in morrowind...as an expansion. In daggerfall there were also wereboars and werebears. In oblivion they didnt add them at all. it just seems like they are a guilty pleasure bethesda would rather not see implemented all the time.

Probably. Its a popular feature and it has connection to a Daedric Lord.