The thing for me is that runs in BoI or FTL are short enough to almost be considered single levels in the larger game of seeing new content and unlocking shit. Being sent back to the start of a level when you die is fairly reasonable.
Dungeons of Dredmor took me a good ten hours even with
permadeth off. To me that's just too big to justify invalidating the player's former progress on death. I'm not surprised modern Roguelikes like Spelunky and BoI are moving towards a more accessible action style of gameplay. It just makes more sense to me.
Now if you'll excuse me, I'm going to go roll ten dice until they all come up sixes, because apparently trying to be lucky is exciting.