The thing is computer games are in a unfortunate position. When we see gorgeous people they are usually in still shots takes as still. Like a model at a photo shoot for a magazine cover or w/e.... but computer games are more like films and more than that that are trying harder than ever to mimic real life.
The problem is that in real life, if you freeze frame candied pic, of even gorgeous people, they look ugly as fuck.
Now these are extreme examples but you could pick any actor and if I could be bothered I could find frames were they look terrible even though they are very attractive people and look great in the same sequence the frame came from, when it is moving.
This is just how reality works and the odd stills we see in various video game threads are cause in part by the fact they are starting to mimic reality more and more.
Added to that is in MK they are telling and screaming and grimacing in pain... all these do not make single frame grabs as appealing.