I posted this in a thread a while ago, and I'll repost it here because my sentiments are still the same:
Mortal Kombat was more of a casual fighting game - fun to watch for the fatalities/blood/gore, easy to pick up because all the characters controlled the same outside of specials. As the series progressed, Midway lost track of that, and tried to ape other fighters, incorporating parry systems, different 'stances'(up to 3 per character in some games), long chains of dial-a-combos, ridiculous subsystems, etc. The bitter cherry on the Mortal Kombat sundae was that this was all layered on top of an inherently broken fighting engine. They tried to go technical like VF, SF, Tekken, and SC when their fan base didn't want that to begin with.
Over the last 10 or so years, I think there has been one Mortal Kombat game that has stepped back towards the right direction, and that is Shaolin Monks. Adopting a more casual friendly, Power Stone/Smash Bros-type of play style worked wonderfully. You had you're easy to pick up controls, the brutally awesome fatalities, a fun and surprisingly compelling campaign that just can't be done in a traditional fighting game, pretty much everything that the other MK games did wrong. The next Mortal Kombat game should go that route, with stories for every character(the one thing the series has always done decently well), a 4 player brawl mode, co-op, etc.
