colours are an aid that can show you the value of an item, when in dungeons or the in world looting mobs, i know to loot greens for DE, blues to sell, and epics to sell for a high price, if colours are removed, i have to check every last item in my bag to see if its junk/DE/sell/sell, the current system i know what is what simply by the outline colour around the item, if i lost this i would be annoyed and i'm sure others would be.