Like with most mk games a number of characters have similar attributes. similar powers or moves.
So with a few new costumes or facial changes, martial arts swap arounds and power shuffling on the existing mkd line up we could have had triple the characters. Now i know extras like this can decrease quality but much like monster who was purely a costume change of scorpion, you could costume change, power and style changing using the exisiting pool of preprogrammed atrtributes, eg: animations, sfxs,
Let me explain my increased character selection using trickery:
For example you take nightwolf, give him a costume similar to shao khan. Allow him to use his shoulder slam power (possible changing the green glow color to red or something but really not needed, remove the arrow powers (give him another kind of projectile from another character) and replace the axes with single sledge hammer, much like can be picked up as a stage weapon. Then replace his styles with 3 random styles selected from all the styles created. Then you have an instant shao kahn, without any of extra work except a name change, costume change and bit of shuffling.
This works for others such as Smoke, he can become cyrax, seketor etc....
Scorpion could be reworked into reptile and rain,
Jadecould be reworked into kitana,
Kira could be reworked into Sonya,
Raiden or shinjinko into fujin
Lui kang could be reworked into Johnny cage,
Darious could be reworked into jax etc......
Basically its like a revamp of the old pallet swaping, where you double your character list, but limit the amount of individual 3d models and use costume changes (which use less memory), like the Monster in the nexus and reshuffle powers around, and styles to create all the new characters. Remember all the animations and styles are in the game and are assigned to a basic 3d model like shujinko uses animations and powers of others it could be basically triple the game, still allow for good quality and keep memory and effort down. Not to mention allow for everyone to beable to choose there favourite character.