I enjoy the interface of HD DVD more than blu-ray. And yes, keep in mind this announcement is for Warner for their release of movies.
HD DVD with 15 gigs, can have roughly 6-8 hours of video. This is plenty for any movie out there, i have yet to watch a film that is 6 hours long. Storage is indeed a non-issue for movies that are professionally released by studios.
It is really between, the consumer buying a studio disc, vs. the consumer creating their own discs, either video or data, which has nothing to do with this announcement.
The storage debate is only for people who want to do data or produce their own discs, and in this case, blu-ray is better. But for which is better to watch a feature film on, they are the same, because both will take up the same space regardless of how much you can put on the disc.