Bo Rai Cho farts and puke = useless, Rain not so much.
I think it is silly there are only female Edenians in every game, Rain is a perfect male Edenian, he has cool parents as well.
Weather is more than just lightning and wind, Rain doesn't control wind at all, he controlls the more story watery weather such as clouds, rain and lightning, not wind (as far as I know)
Nobody cares about his ninja-features, he already left that stadium in Armageddon when he became more unique.
A lot of people love the colors in this game, and purple is always a favorite. So that helps as well, also rain looks totally awesome in MKX and MK Armageddon.
Sub-Zero and Frost control cold and ice, not water, they can freeze water, not control it.
I know you just hate on Rain, but he's the perfect character like so many others in MK.