Just to see MORE.
Icons are often useless and only take space which could be used for text. Console has no icons and we happily use it, so why are we forced to see pixel piles when mousing?
16 pixels is relatively small, but when you have fonts size 3-5, that's a relatively hefty lump of pixels gone to waste. Especially vertically, you could fit a lot more data on screen without this size limit.