I wonder how many of the packrats who cannot bear the knowledge of a dungeon cluttered keep their bedroom equally tidy. I am certainly not one of them. How can this chore be such a compelling aspect of a game?
Ah... Because it is part of a process that culminates in higher numbers (equipment boosting stats, or equipment sold to boost wealth to purchase equipment boosting stats). I suppose.
The awful fact is: I find tidying up dungeons as tedious as I find tidying up my bedroom, and not half as rewarding, yet I surely do it more frequently, tirelessly and thoroughly.
In order to enjoy games more and waste less time, I leave more loot. And learn to live with it.
I'd be perfectly happy with a game that put "Infinite inventory space" on the gameplay/preferences options screen, though. Have a meaningful limitation by default, without making the game depend on that, and let those who still wish to clear the dungeon do so in relative comfort. (Oh, maybe that's the real drive: Accomplishment. Finish the level, clear the dungeon, score 100%.)