Let me ask you this. If MKX Reptile was like a horror film villain or fantasy film character, would you dislike the design still? Same storyline. Ancient lizard man race who fights in Mortal Kombat tournaments to the death.
Kind of, yeah. It just looks poorly put together. Some of the textures look stretched or abnormally flat. His eyes often look misaligned, and the hood without the mask looks extremely dopey, like he's wearing a low level helmet from an Elder Scrolls game. And the mouth/lips remind me of a wisened old man with a long face and hollowed cheeks, sans the sharp teeth.
It's too ugly to be cool and too messy/goofy to be intimidating. Maybe it'd look better with a different costume, but as it sits, I'm really not a fan. Whichever way I look at it.