I wouldn't say the roster is bad, more like the omitting of several fan favorites is rubbing people the wrong way. People probably wouldn't be complaining about characters such as the Brigg's and Cage's had other, more eclectic characters (such as Cyrax, Smoke, Fujin, Sareena, etc.) gotten in as well. Sometimes I feel like the story actually gets in the way of MK, and NRS forgets that in the end people just want to play as their favorite characters, regardless of whether or not it makes sense in the plot.
On that note, if the plot is THAT important why not make certain characters unlockable? It's just trifling to see four characters using military themed devices when you could also have had Smoke who's enenra form makes his possibilities limitless and unique. I can tell you right now, if I see Jax or Jacqui toss out a grenade I'm going to scream.