I think Diablo 2 is a hack-and-slash. I like it for that though. The story and quests bugged me because they all interlocked to a point where there were all the same. "Find the secret of the Dark Tower", "Slay the evil Mistress", "Find the Treasure" were all the same quest. You could not complete one without completing all three. There's half a chapter done already! I still did the quests of course. Experience is experience and gold is gold.

I also think that Diablo is an RPG. You are one person working yor way through the story, developing yourself. Some D&D campains are nothing more than hack-fests, but you still develop your character and they still have their little traits that you impose on them.