I like the idea of the Roguelike as a procedural dungeon crawl where emergent or otherwise interesting things can happen. What I don't like is that almost always Roguelike gameplay consists of clearing everything out, becoming as powerful as you can, and then overcoming some final challenge that you had no chance of defeating at the start of the dungeon.
To me, dungeons aren't a place where you go to gain in power, and if you weren't prepared to defeat the big bad from the start, why did you come here? It's a weird compression of the level 1 to level 20 DnD arc within a single dungeon.
What I'd prefer is a game where you start out powerful and prepared, with the challenge being in
keeping that power and preparedness through challenges that wear you down. Rather than fighting everything you can for exp and exploring every room for items all so that you can grow strong enough to defeat future enemies, you'd want to avoid conflict and just try to get closer to the end without wasting supplies.
This would mean a shift in gameplay away from straight combat towards stealth, survival, and possibly diplomacy. Fighting the tribe of horrible nasty frog people means digging into your supplies of antivenom, helping them out with their problems might get them to help you instead.
This would also lend itself to a preparation phase before you start the dungeon crawl proper. How much food will you need? How much water? How much lantern oil? Maybe you can hear rumors about the dungeon and make more special preparations.
I don't entirely dislike the idea of finding things that let you gain in strength during the game itself, but it should be the exception rather than the rule. Or rather, a gift from the RNG rather than a core gameplay mechanic.
Things like unique magic weapons beyond anything you could find in the outside world, or sinister magical rites to help you survive just a little longer.
Closest thing I can think of to this idea is Darkest Dungeon. I'd prefer something with more non-combat gameplay, more procedural elements, and no metagame between runs though.