You've got your terms mixed up. HD refers to the resolution, the number of pixels, not the image quality.
If the image is blurry or has digital noise (that ugly grain), that would be because the lens / sensor are super small and simply not very good, but you can still call HD anything with a minimum resolution (1024x768 for 4:3, 1280x720 for 16:9).
So as long as the camera meets an HD resolution it's technically HD, so you couldn't call it deceptive marketing. It's just bad HD.
I'm personally coming from a 2011 MBA, which was a regular "FaceTime" camera, no HD. The one in my rMBP is definitely better, but still pretty bad.
I think it's simply impossible right now to make a camera that's considerably better than that in such a small form factor. I mean place your fingers and just look at how thin the camera unit sandwiched between the aluminium and glass must be.
As someone who rarely uses his webcam, I'd rather have a bad one than having a thicker laptop just for the sake of having a better webcam. Otherwise I'd just invest in an external unit which will be better than any laptop webcam by a long shot.