I don't really buy the epicness comparison arguments, because one could say the exact same thing about running into things like mindflayers, minotaurs, beholders, and githyanki, with your party at that point already accepting that they're part of one really fucked up adventure to begin with. It's really just a matter of what the story and setting is trying to convey, and there's nothing inherently wrong with this unless it's a total thematic whiplash, which isn't happening in either game.
