First the majority are in 720. The ones that are in 1080 tend to be 10GB to 50GB in size and downloading them can take days (I've tried - on a decent cable modem connection). Then you need to store these beasts which means some sort of multi-terabyte storage server - or burning them to Blu-Ray or HD-DVD disk. A perfectly acceptable alternative but then you're not usually using an Apple "iTV" as your playback device.
So so far this is so far out as an edge case that Apple's choice still makes sense.
Take a look at their "High Res" movies
http://thepiratebay.org/top/207
First the majority are in 720. The ones that are in 1080 tend to be 10GB to 50GB in size and downloading them can take days (I've tried - on a decent cable modem connection). Then you need to store these beasts which means some sort of multi-terabyte storage server - or burning them to Blu-Ray or HD-DVD disk. A perfectly acceptable alternative but then you're not usually using an Apple "iTV" as your playback device.
So so far this is so far out as an edge case that Apple's choice still makes sense.