'Apple could do an HDTV' speculation still doesn't answer the real question

I’ve seen articles like this one from Dan Frommer at SplatF come and go for at least five years. They all toss out a bunch of great ideas for services that Apple and TV providers could offer, or different ways existing services could be packaged or changed.

But I have yet to see a piece that tackles the real question: why would all these great service and product ideas require Apple to produce a full HDTV set instead of the very capable $99 box it sells right now?