ToME is a lot easier, but also defies most roguelike conventions to some degree, so it's not exactly a good representation of them.
Nonsense. ToME is neither easier (try getting a cursed class character to level 40 and we'll talk) nor does it defy any "conventions". ToME
was easier some time ago (before version 1.0 I guess), but I would say that at this point it is only easier in the first dungeon. After that, I die about as often as in any other roguelike.
It is easier accessible as it offers an actual freakin interface and controls that have evolved beyond "each key on the keyboard has a vital function so you better learn them all". If you are one of those "mouse is for retards" purists, well, whatever, but I am certainly not.
You might be talking about the "fact" that a character in ToME is not permanently lost after one death. But that can be changed when starting a game to be one life only. The default setting is called adventure mode where you start with 3 lives (I think) and get a new life every 10 levels or so. I play both modes, whatever I fancy when starting a new game. There is also a mode with unlimited lives.
This does not defy anything, it offers more options.
And besides, it is the best looking roguelike out there (among those with tile graphics, that is) with some pretty good music and sound effects.
All of that said, if you want a more classical approach to get started,
Dungeon Crawl Stone Soup is always fun.