There are plenty of MMOs with solo progression that aren't one-and-done or repetitive at all.
And I'd kinda argue that Torghast isn't really a good example because it can be repetitive regardless of group or solo. I love roguelikes and all but Torghast doesn't rub me the right way for repeat playthroughs.
Hard to put my finger on what it is too, because it has all the makings of a good rogue-like, but it's like they don't take it far enough to making it a truly enjoyable repeatable experience. I think it might be because of WoW's reward system and the feeling that you're playing for the sake of the breadcrumbs rather than because the roguelike experience is actually enjoyable.