Please show me the other players that love having important quest items mixed in with everything else in their inventory to be sold, lost, etc. You said there are lots of them, so go ahead.
I'm one. I'll take it one step further, I'd rather the game didn't tell me what the key I just picked up is for. Seriously how the hell does my character know that that particular key is for an ornate chest?
I can see myself trying a door and finding it locked. Then I open my inventory and move each of 100+ keys from my inventory one at a time to see if any of them will open the door. Then after 20 minutes of completely wasted time and frustration I push myself away from the PC and my chair runs over the cat, killing it. Why do you hate cats?
I believe the frustration sometimes also stems from the fact that the game only checks the keys in the character interacting with the door. Meaning if Rodeerick picked up the key 5 mins ago, and Scarlett tries the door, it will remain locked.
Player would be fooled into thinking they don't have the key, when in reality they do.
But usually I just fireball locked doors. Easier that way.