Related to the comments about Armageddon.
Not much about the limitation of the game engine itself but it's more the fact that he was a nightmare to animate in general.

They used mocap for the fighters basis which later was tweaked while this being a half animal monster human, 4 legs, means it would be nuts to put together.
They already were busy with animating bunch of stuff for Armageddon and this on top would be way too much.

And when you look at the other non-fighter animations in that game you can realize that the devs were not that much capable of animating anyway.

Instead of animating from scratch or stitching 2 by 2 together they used a easy exit of a generic character animation setting and be done with since it was kinda a throwaway character anyway ...

And yes that on his hips plus crotch, metal looking layout that further stretches through his bottom part then forms into his tail collectively is a flamethrower device of sorts.

We use to joke around that part collects his fart gas and enhances it then flames it up which as a result becomes a projectile from his tail. XD

His bio or ending (can't remember which one) in Armageddon alludes to the developers not liking him or something.
And being his only real appearance in MK9 was lying dead on a stretcher kinda confirms this imo.

Edit: And in this scan it says that the weird thing on his waist is actually a flamethrower.
https://lh3.googleusercontent.com/pw/AJFCJaWH5HRFvGCneCv9EkJDoGUENwGF6fCUrRc5bpUxilIF9x6RgwdUXphCJrg6P0pa29xNGqK51UoGq2mDslPAG1yFS0hoJpHiq_uxwmY6q8kRkMk6PT0=s0?imgmax=0

@Alxala. Yeah. The only reason he had two legs in Armageddon was due to limitations with the engine. (And given a cheesy in-universe reason for it)
With what they use now (Unreal Engine), it shouldn't be a problem to make him a centaur again.

I would love to see this version of Motaro on MK12! That would be so badass.