My iMac has 4 cores. I'm not constantly complaining about nothing being available that seems to max them out.
From the beginning the current

TV had 720p hardware, but there wasn't constant complaints about no 720p content in the iTunes store.
Today, Jobs rolled out 99 cent programs, packaging it as some sources that are playing ball and others who are not. He could just as easily rolled out 1080p hardware and mentioned 1080 camcorder home movies look great, several podcast videos are available in 1080p, youtube 1080p is available etc. "We are ready to offer 1080i/p content as soon as any studio wants to add it to the iTunes store. In the meantime, all of our movies and TV shows are now 720p..."
That would have shifted the complaints to the Studios, because Apple would have covered the part they have control over.
And my money would already be spent. And I'd be gushing positives about "finally...", etc.
You seem to perceive that a hardware announcement today would have forced everyone to start dealing with the "problems" associated with 1080p file sizes. Those with limited storage could download 720p or smaller files. Those with limited bandwidth could download 720p or smaller files. Etc.
A simple message on screen could educate the buyer/renter that the 1080p version are very large files and will take a long time to download on slower broadband connections. Those that want to anyway could still get what they want. That would be much preferable to Apple deciding for us.
A 1080p chip set wouldn't have to affect anyone who doesn't want to deal with the negatives of file sizes, download speed, thinner broadband pipes, etc. The whole iTunes world could keep choosing 720p or SD video... and it would play to the max on hardware capable of better than those standards.
But it doesn't work the other way.