Let’s be clear about something: The MMO genre does not have zero overlap with the roguelike genre. I mean, the Diablo games exist in the larger genre space, after all. But there are also a lot of games where that is definitely not the case. Sure, it might suck when you continually fail to get the Sword of Dismemberment from whichever raid boss is annoying in World of Warcraft this month, but it’s not like you’ll be getting a random drop of that sword from a disgruntled goat.
As a long-term prospect, MMOs tend toward predictable content with predictable outcomes and some randomness around the fringes, but if you’ve leveled through a game dozens of times there might be some fun in having your rewards and choices be random and narrower. So are there any MMOs where you’d like to play a roguelike mode? Not as a side channel of content in addition to the main game, but a mode existing alongside the main game with a nice slice of randomness?