I've been experiencing the same thing, maybe it's because I always thought Sonya as one of the lamest MK trilogy character and Johnny Cage as a generic character with no excuse for what he does, and the combination of these two plus some new things some way created a interesting one, like both of them were not good but together they make a whole, with a few retouches of course.
And besides, judging by Cassie and Raiden's intro, it seems we are getting a better explanation for the green energy powers.