Why haven't I been playing Mystery Dungeon before now?

[DysfunctionalDragons]

Rhetorical question, actually.

I'm a Nethack player. For those of you who don't know, Nethack is the king of all roguelikes, and one of the oldest and longest dungeon-crawler games in existence. I've been playing the game ever since my mom showed it to me when I was eight, yet I still haven't beaten it because it's just THAT hard. Despite this, it's a lot of fun, and from time to time I get a really long game going.
Anyway, when I first played it, it was during the first wave of Pokémon madness, which I was a part of, so like all times I had been obsessed with multiple things I found ways of combining them in my mind. I thought it would be really cool if my pet were a Pokémon rather than a dog, cat, or horse. In fact, all the monsters should be Pokémon as well, and the final boss should be Mewtwo. I told my parents (electrical engineers) about it, and they said no, even though the source code was open, they would not hack Pokémon in it for me and I should do it myself if I were so inclined. Of course, I was eight, so I wasn't smart enough to do that by myself, and I'm still not— I may like computers but coding has never been my thing— so I didn't seriously attempt to do that. I still thought a Pokémon roguelike would be awesome though.

But even after I got back into Pokémon with the release of Diamond and Pearl, I ignored the side games, so I didn't notice that there now was a Pokémon roguelike in the form of Pokémon Mystery Dungeon. How silly of me! Though I had some real-life friends still into Pokémon in general, none of them were Mystery Dungeon players, and none of them could inform me on the awesomeness of this game. I didn't investigate it myself until recently, when I was allowed to request one DS game for Christmas, so I picked Explorers of Time. I am unashamed to say that it has completely eaten up my last week, and though my inner physicist cried at the nonsensical time paradoxes, I've been incredibly happy with it. It's everything I wanted in a Pokémon-themed roguelike and more, since they combined the two games' mechanics in what seems like the best possible way (though the death penalty probably should have been harsher— in other roguelikes you LOSE EVERYTHING, EVEN YOUR SAVE FILE when you die so PMD seems downright easy in comparison). I love everything about it except for the music, which is listenable but not as good as the music for the main series games (I may think of using the Temporal Tower leitmotif somewhere in the Divine Medley, though, if I can fit it in— not easy because it is in a minor key but most main series battle themes use mostly or exclusively major chords).

So to make this post more than just pointless gushing, I'll ask a question. Have any other Pokémon Mystery Dungeon players here ever played another roguelike, possibly but not necessarily Nethack? What do you think of the differences?