But you're missing the point. Your Mac is the Media Center. iTV is simple a device to allow all your media on your Mac to be displayed. The last thing Apple is going to do is build the iTV into another computer when we all have our Macs already. Keep the iTV as simple as possible to wirelessly display all your content on the TV.
I started out a proponent of the "add a DVR to the iTV" concept, but I've since come over to your way of thinking. I do want to see the iTV be "platform neutral", however -- capable of working well on both Windows and Mac platforms. The key, I think, is iTunes. I believe the iTV will take whatever iTunes will feed it, on whatever platform. If you can get it into iTunes, you can use it.
I own an HP Media Center PC -- first PC I've ever owned, in fact. I needed it to be work compatible (purchased a few weeks before the Intel Mac announcements -- so much for my sense of timing), so I decided if I'm gonna buy a PC, it may as well be kept busy the 99 percent of the time when I'm working on my Mac instead. It is not a bad little DVR platform. MyTVtoGo software plugin for Media Center brings this content to iTunes for me. I'm counting on iTV to bridge the gap to the TV set.
I think Apple will do the iTV right -- out-of-the-box operational and trouble-free. This was
not my experience with the Linksys Media Center Extender I bought. It never worked once. (Man, I should have sold that last week on eBay. After Tuesday, who on Earth would want one?)
The trick will be to expand what iTunes will do, especially on the Windows side of things. The iTunes podcast subscription model and the iPod Games are great "proofs of concept" that iTunes can be a delivery system for just about anything. If Apple could partner (for example) with Google to bring YouTube's content to your home TV via iTV and to your pocket via the iPod, it could be a pretty sweet deal. An independent on-demand video service with original content would be even better. Apple's massive iPod market share makes that a possibility.