Lots of us have 4K TVs (or even 5K iMacs). And we've either been shooting 4K on 4K camcorders and (the other guys) smart phones for the last few years or we've started shooting lots of 4Ks on our new iPhones (millions and millions of us apparently bought a 4K-capable (new) iPhone in the very first weekend it was available). As such 4K content will explode on sites like youtube. iMovie & FCPX will edit our 4K home movies shot with our new iPhones and we'll wish we had a "just works", easy way to display that 4K on the 4K TVs we have or will buy soon (I don't know where you are but where I am it seems there are more 4K sets in the stores than 1080p, and prices are much more interesting than typically implied around here).
Besides, Apple goes 4K and that lead will drive followers to roll out 4K content. Apple goes A9 and loads of followers code apps for A9. Apple goes smart touch and loads of followers code for smart touch. Apple goes Apple Pay and lots of partners pile on in support of Apple Pay. Apple goes retina and loads of followers develop for retina. Apple goes TouchID and developers embrace TouchID. See the pattern?
On the other hand, no partners lined up in support of Apple Pay BEFORE Apple chose to develop it. No partners coded for A9 before Apple chose to develop it. No partners supported smart touch before Apple chose to develop it. Nobody coded for retina before Apple chose to go retina. Nobody supported TouchID until Apple chose to embrace that. Again, see the pattern?
If Apple had embraced 4K here (like they did in just about everything else they sell), the Studios would have wanted to roll out 4K content in the iTunes store. It makes zero sense for the Studios to roll out 4K
TV content in the iTunes store until there are 4K
TVs that can play it. Apple should
lead the way there (again, they've already embraced 4K in just about everything else). Some of us are grumpy about this because A) we believe Apple SHOULD lead the way and B) after 3 years since the prior
TV rolled out 1080p, we expected Apple to go ahead and make the jump instead of another round of 1080p. Plus some of us with 4K sets are hungry for more 4K content and would rather buy/rent it from Apple than Netflix, Amazon, Youtube, and the new 4K Blu Ray discs.