Abrams could argue that most people who see the film won't care or have even heard of the augment virus...
Why would he wish to make that argument, though?
... but some fans will care and for the integrity of the franchise, the Klingons should not have cranial ridges.
Some folks do have some interesting notions concerning "the integrity of the franchise" but, as has already been pointed out, nothing seen or said in any previous episode or movie precludes the appearance of bumpy-headed Klingons in the upcoming movie. Or smooth-headed Klingons. Or a mixture of both, plus
some never-before-seen pointy
Bring 'em all on. "It is a good
day to put your opponent's eye out with that pointy, pointy head!"