DVDs ended up on desktops because computer makers thought that the massive capacity of the disks would naturally lead software developers to put out titles on DVD. (Remember, they’re “Digital Versatile Discs.”) They were way-off. The quantity of DVD-based software is marginal, and even DVD audio is only just getting going. DVD movies have dominated the technology, and thus have become most closely associated with it.
Compare this to CD-ROM, which is cheap, ubiquitous and handles both audio and data well. Economy of scale has allowed manufacturers to bring the cost of recordable CD-ROMs down to within everyone’s budget.
DVDs will become standardized as the “only” storage device, because DVDRW (or whichever format wins out) will eventually come down in price, show up in consumer electronics and displace the VCR, even, as the television/movie recorder of choice.
I predict by 2004, there will be no more VCRs made; all new video recorders will be of a Tivio-like device: a hard-drive for temporary storage of a day or so of video, and a DVD reader/writer for playing and permanent storage.