On CRT, interlaced works fine. And there are certainly more CRTs out there.
If the future was CRT I'd tend to agree go interlaced with the downloads.
1) when it comes to Widescreen TVs, the majority are progressive (ie Plasma or LCD).
2) Our laptops, iPods, iPhones are progressive.
3) Interlaced TV shows use less bandwidth (not half as you say, but certainly less), but this is because they cut out every 2nd line... which is ideal IF it was filmed that way
4) Film is done progressively. Typically 24p. This gets converted to 60i. The compression of the original 24p uses less bandwidth than compressing the 60i version, and looks better.
I'm struggling to see the advantage...
Okay... it'd be great if Apple catered for the millions of existing users out there with CRTs and 4:3 screens (users like me, actually) by providing a much smaller TV file that's lower res and interlaced (for any show that was filmed interlaced)
...BUT I think Apple should cater for the new markets of 720p and high bandwidth. Perhaps they can do both.
Am I missing something?