The one consistent thing I've seen with the vast majority of HDTVs is that many of them cannot show a basic computer image without messing up the display in some way. For example, many "1080p" HDTVs arbitrarily limit the VGA input to 1024x768, and there's also models that arbitrarily subsample input to 4:2:2, which introduces color fringing. (Just try using any sort of program that displays text on that!) Virtually none of the displays I've used that are marketed as standard monitors have these issues.
What I'm wondering is if Apple's "HDTV" will actually be usable as a standard monitor, or if they'll use the same garbage decoders found in the rest of the dime-a-dozen displays. If they do use a standard monitor decoder instead of garbage, then it might actually be worth a purchase, regardless of the brand name or extra iOS functionality. (Obviously it would need to actually support various inputs like VGA, YPbPr, etc; a Thunderbolt-only HDTV is kinda useless.)