Hm, you say the point of the rename is to not make people feel they miss something when they start the game. But the fact is, they do miss a lot. As I'm not a prerelease tester, I haven't seen what it's actually like, but I say this based on what you've said about the game mode. Deadly hunger is an important game element. Talents add a nice flavor to character customization. But the most important change, I think, is the "pampered" dice rolls. They could potentially greatly affect how you approach the game and certain situations in it, simply because you're much less likely to encounter certain situations, like say, something drops you to 20% health instantly and you make a mental note: okay, I need to be more careful around these monsters/doing this stuff. Maybe I should use different tactics settings? Or try ranged combat? It's too fast to stay in range, can I slow it down somehow? If a monster is less likely to, say, shrug off bolt spells, then the player's less likely to experiment with other stuff he has access to (ball spells/wands, throwing potions etc.). As always, difficulty inspires creativity and exploration of game features that might otherwise stay unused.
Now I did find the Easy/Classic naming scheme to be fitting, because it guides the players toward the standard game experience. And if someone doesn't care about playing on full difficulty, well, they're free to play "Easy". Personally I always play games on the hardest setting, and if I get what I bargained for, I don't complain. I'd imagine if someone doesn't specifically need the challenge, they would be more comfortable with playing "Easy" mode.
But then again, maybe you're right in that "Easy" discourages that setting too much in the middle-ground of casual/hardcore players. But I think calling the other setting "Hard" doesn't offer that subtle nudge towards the player, or rather that middle-ground type player: "Hey, once you're comfortable, give me a try." The existing fanbase indeed does know what it wants to play. But the prospective fanbase does not, and some of those who would enjoy the "classic" mode (after getting used to the game a bit), might not try it without some encouragement. So I propose the following:
"Tutorial (easy)"
"Average"
"Classic" or "Classic (roguelike)"