you don't understand. AppleTV is here to pave the road for future products. But the future will be not one product doing everything (MS style) but a set of products doing a couple of things very good. If you wan't everything you describe buy a Mini, a second external hard drive or something like this.
Apple TV is a way to capitalize on the iTunes-iPod success and putting your content on the most widespread electronics device, the TV-set. it's that easy, it really is.