I think we need something to increase the importance of player tactics (I'm not referring to the 'tab' tactics thing). At the moment, the early game is a test of attrition rather than skill - you get lucky as to whether you open a door on a caco/Hell Knight/Former sarge, and there's little variance in tactics a player will typically take in subsequent games (e.g., unlike Nethack, Angband, etc, I can't say 'Okay, I died trying to simply attack the bad guy from a distance last time, this time I'll try disable it somehow before attacking'). It gets a little better later on, as the variety of weapons and the amount of traits allows for some level of tactics, but it's not enough, in my opinion. Too much of the game is luck-based rather than decision-based.
So I'm suggesting we add something in that goes alongside Traits, but works differently. Perhaps something akin to a 'magic' system - except it won't be 'magic' but rather things such as 'Aimed Shot' (Next shot has 99% accuracy), 'Increased Perception' (to temporarily increase sight range), 'War Cry' (brings monsters coming to your position).
To those who will say 'Oh no, it's outside the scope of Doom': I'm sorry, but the scope of Doom, as it is, doesn't translate all that well to Roguelikes. There's no (in any useful degree) ability to nimbly dodge an imp's fireballs by strafing, no ability to shoot furiously while backing away from an oncoming demon.
To those who say 'But it's a coffeebreak Roguelike!' : If you're going to use that as an excuse, what's the point in continuing to improve it at all past its original release? If you're going to do something, it's worth doing it well.