How is it useless? As movies get longer/get better quality it'll use a lot more storage, space is totally relevant, and BTW ever hear of extra content?
How can the movies get better quality than the resolution of most available HDTVs? Do you really think they are going to start making higher resolution TV's than 1080P in the near future, even if they did make the TV's the amount sold would be small and hence movie companies would have no incentive to encode movies at the higher resolutions.
How much extra content do you really want? The amount on most HD/Bluray releases is similar in content to that available on DVD's and right now I don't watch any of it.
The only thing I really care about in terms of extras on movies is the commentaries, and they don't take up that much space.
And my point is still valid, Blurays at the moment usually don't have as much extras as the HD-DVD releases so how is extra space going to change any of that.
Seriously I don't get the hype about extras.
BTW 1080P resolution in a TV screen the size of 32 inches is fairly useless, unless you sit like less than 1m away from the television the human eyes won't be able to tell the difference.