Interesting imagic thanks for posting this.
I agree this will be the case for some displays. I remember the quality of a 50" 720p 8G Kuro looking far more detailed than a 1080P LCD for (everything) except (perhaps) 'digital stills'.
But even then if the digital stills were dark, or nearing black then the 720p plasma still won the day imo.
In other words anything with even the slightest of motion, the "lower" res plasma hammered the 1080P full HD without even trying.
It comes down as always to the most basic of reasons for image quality...
Colour saturation (red reds),
Colour accuracy (skin tones),
Motion resolution (plasmas
Display resolution comes last on the list.
But another thing we realistically need to take into account is that the human eye with regard to distance resolution, after all as the old saying goes, what's the difference between 720p and 1080P - two metres apparently - so that's another thing to take into account.
With the sheer quality of panel on my KRP500 - on HD and especially 1080P - i need to be sitting closer than a foot to notice the pixels however.