Even said so myself. A bit quick in replying there uh ?
Not at all. I was simply *agreeing* with that part of your statement. Hence the 'yep'.
Since they coined the term, they can change the "normal viewing distance" of any screen to fit the definition and baring that, change the whole definition and pretend it's always been like that.
Actually, not. There are studies which have been done about how far people typically keep certain size screens from their face during normal usage scenarios. It turns out that it is *largely* dependent upon screen size, and how much of your field of vision the screen takes up. For hand held screens, with users who have typical vision, the ranges are pretty narrow, and are consistent with the numbers Apple has used in their retina calculations.
For desktop/laptop scenarios, the ranges are substantially broader, until you break them down by 'working' vs. 'viewing'. At that point they get more consistent, with the 'viewing' range (when someone is sitting back and just reading, and maybe scrolling, through something), typically 1-1.5 feet further back than their 'working' distance, which is (again) largely dependent upon screen size.
TVs are where this breaks down, because the two major distance factors with TVs are: the size of the room the TV is in, and the size of the screen the people can afford (or justify to themselves). Most HDTVs are already well beyond 'retina' at the distances people commonly view them. (My own 46" TV, for example, would still be retina if I sat on the near side of the coffee table rather than the couch. If I wanted a non-'retina' TV at couch-distance, I'd need a 75" set or larger, and I can't justify that to my wife even though she's the one who watches more TV.)