Because they have half a clue
Apple doesn't enter a market unless they see the ability to innovate and change it. They aren't always first movers, but they DO bring innovation and of course profits to any segment they enter.
The magic is in saying "NO" to doing things that don't make sense... entering a crowded, unimaginative, razor-thin margin, mature TV market doesn't make sense for Apple. That's why they said no.... No more, no less.