J.J. and his writers are no fools groping in the dark with little or no clue. They've made Enterprise
references in both of their films thus far and I'm sure they all know about the ENT explanation for why Klingons had smooth, more humanlike appearances in the era of the original series. I'm sure if he and they had wanted to mention something about the Klingons' appearance in STID they would have, but the Klingon scenes were all related to intense combat and the capture of Harrison/Khan, so it's not as if there was any plausible reason nor even the time to have Uhura or Spock or Kirk mention something about some Klingons not having cranial ridges when the focus of that whole sequence was the running battle on Qo'noS and Khan kicking some major ass.
If it happens at all, there'll be a more appropriate time and place for the forehead issue to be spoken about.