If 4K is a gimmick and not necessary on the new Apple TV, why did Apple come out with a 5K 27" iMac last year, reportedly a 5K 21" iMac next month and 4K recording on the new iPhone 6S. Why are Apple fans picking and choosing why it's innovative on some machines and totally unnecessary on others. That argument doesn't make sense to me and judgements to the contrary are totally arbitrary
It makes sense to have 4K (or 5K) when you're sitting a foot or two away from your display... and where more screen real-estate / pixel-density matters. (And, where video editors are starting to work with 4k source footage.)
When you're sitting on the couch 6'-10' feet away from a <60" screen, it's irrelevant.
Context matters.