I generally don't mind the asset reuse, in fact it can be fun seeing the ways devs go about recycling things... but in the case of the Blasphemies I have no choice but to agree, it was kind of a letdown. The first two bosses of Vanaspati feel like the only ones that were designed for the job (and they're great!) whereas everything else is just, as you say, old enemies they didn't even really change much... It's especially egregious when you get to the Role Quests and even those don't really have anything unique going on.