Agree to disagree, I suppose. I've played dungeon crawlers where that wasn't the case (such as Diablo 1 and 2). Torchlight suffers from an overbearing lack of variety in my opinion.
Diablo 1 wasn't repetitive and the same monsters over and over? Since when? Where do you think Torchlight got the idea. Diablo just recolored monsters as you went down levels. Sure, there were about 5 or so different total levels which added a bit of new monsters... but I think you are letting nostalgia cloud your visions of the game. Even Diablo II suffered from the copy/paste monsters. It's a genre issue more than anything.