I know this would be nearing variant territory, but I think static quests would add a lot to the game.
Randomly generated levels are good since you dont know what to expect, but a cleverly designed or themed level (like, orc cave, dragon lair, etc.) can have better gameplay than a random dungeon.
Uniques shouldnt be on static levels, so the reward from unique drops would still be higher in the real dungeon. The only problem would be that you would know what to expect, and scum them for experience (until you run out of gold from the worse non-unique drops).
Static Quests
I actually think that this is already in there, part of the Ironman changes Jug made several years ago. There's a special file you create for each level you want static, and when that level is created, it'd done using that file as the template. I haven't ever worked on the function, but others might be able to help you out if you want to figure out how it's done.
Good luck to implement static quests in Mang... it works fine in vanilla Angband where there is only one player and you don't have to figure out which player has completed which quests and which levels should be static for which players...
The only easy quests to implement (see PWMAng) are random quests (kill n of the foo race)...
The only easy quests to implement (see PWMAng) are random quests (kill n of the foo race)...