I prefer the revisionist approach: that if that period of Star Trek were made in 2008, then the Klingons would have looked like they do in TOS onwards. The Enterprise explanation was fun, but really a bit 'fanwanky!'
I take the approach that the stories and concepts are what matters. It's the same as if I go to an opera: the New York Met version would have one look and the Bayreuth one a different look, even though the music and story are essentially the same!
So, I'd like to see the ridged foreheads on the movie Klingons, although, given the Romulans never had those dorky foreheads in TOS or the TOS films, I'd rather they had the same look as the Vulcans!