It would extremely nice if this could be added as an in-game option, without requiring mods.
Either giving the option to lock hotbars to certain things (Skills, Scrolls, Potions aso.) or to just simply not add it automatically.
Especially skills that add no skills, such as flight, suddenly don't show on the hotbar because of some random items I picked up or transferred between characters.
This is truly one of the few things that has been driving me mad in this game.