Same goes for Motaro. I don't buy for a second that, with all of the technological advancements of the current day, they can't get his body to work within the game. That's a load of garbage. Hell, even Tekken 6 had that goofy ass giant chicken thing as the final boss years ago. They aren't lazy; they just don't know what the hell to do with the characters. Shame, too, because I really wanted to see the Shokan warriors and Centaurs go at it.
It may not really a load of garbage, though.
While the graphics are
different these days, it doesn't mean that it's easier to develop those characters.
Remember, developing for MK9 is much more complicated that it ever was for the MK1, MKII and MK3 flash animation.
In MK9 every character has internal organs, skeletons and bodies that have to be molded for X-Ray moves.
Not only that, but I'm pretty sure that the animation of the characters fighting taxes the console memory quite heavily, which is likely why it's only possible to morph into your opponent and not the whole MK9 roster as Shang Tsung, in the last game.
The amount of character pre-loading to do all of Shag Tsung's possible morphs before 1 fight would be insane, as it would have to pre-load 31 character possibilities.
OT
As for Motaro, perhaps NRS did have too hard of a time getting the skeleton, hind leg animation and internal organs to work properly with the rest of the roster, and thus he was scrapped later on.
We may never know, but it IS possible that Motaro was giving them too much trouble as a properly functioning character.