Vader was established in WCW then, though. Everyone knew what he was about, and Hogan probably knew that he'd look extremely bad if he couldn't at least try to hang with Vader on a similar level. Even then, that first Hogan/Vader match is completely different from the last one at Bash at the Beach, where it went from some of the most interesting work Hogan had done in years to the forumla again. And besides Hogan delayed the Vader feud as long as he could, if I remember, and once it was over Vader was never going to get that spot again.
With Warrior, shit gets bad, I think. Vader worked stiff and Warrior worked wreckless, so something would give. Vader is a perfect opponent for Warrior during his title run on paper and the matches probably would be fun sprints but someone breaks someone else's face.