The inventory system would only be to make sane what we already have. It seems absurd that we cannot, for example, trade the Sceptre of fire between Konrad and Li'sar, or trade the Storm trident between different mermen. Besides the point, some people might want to make their own, much more RPG-like user-campaigns. Why restrict them?
I believe this to be a major change for an aspect of the game that is really minor, but could have very serious effects in changing the nature of the game into something that is really not consistant with its other aspects. How vital is it that units need to change artifacts? Wesnoth has RPG elements to it, but its far more closer to a strategy game than RPG. Being able to trade "artifacts" and "powerups" just seems a bit gimmicky to me and is just a wasteful distraction with little positive value for gameplay and it could entail a lot of negatives (as Ivanovic pointed out)
