One major issue when it came to modding Oblivion was that only one mod at a time could modify a leveled list. This meant that if you loaded up several mods that would add weapons or armor randomly to NPCs, only one of those mods' content would show up in game without using third party utilities to merge the lists. This forced most modders to add all of their items to shops to avoid conflicts. This was enough to get the items in game but you would never see the stuff pop up on NPCs or inside containers unless they were specifically placed there.

Basically I would just like to see a change in the mod system where items are appended to leveled lists rather than have the leveled lists replaced altogether whenever there is a change. I don't believe this is a very difficult change to make and would open up a lot more possibilities when it comes to mods.

Of course, this is all assuming the back-end even closely resembles the old Gamebryo back-end. Personally, I'd like to see a totally new back-end with a much more extensible and fine-grained database. A mod should be fully capable of changing a single record anywhere in the entire game.