Why shouldn't it be?
Not only would it fit that mode well - in the sense of the world around the turtles and Splinter being quite realistic but the comics have tackled fairly heady themes
I realize that people want more humor mixed in so it would never happen but this movie did have its genesis as Batman Begins-esque comic adaption until it went to Platinum Dunes.
Then I am going to count PD as heroes for the first time since this production began. And I have this bag of "no"s. I mean, it's not all of my "no"s, no. But it's quite a bit of the "no"s that I have to my name.
...I feel like you need these "no"s more than I do.