Genre series, like Day One ("V", Dollhouse, Virtuality, Defying Gravity, Kings, Life on Mars, Pushing Daisies, Sarah Connor Chronicles, Bionic Woman, Journeyman, Moonlight, The Middleman, New Amsterdam, Day Break, Jericho, Invasion) really have had a very hard time justifying the resources that have been directed toward producing, promoting and presenting them.
The sheer volume of such shows, over the past few years, is actually interesting, because throughout the 1980s and much of the 1990s, such shows were few-and-far-between. For example, in the Fall 1992 schedule, the only shows that would qualify were The Young Indiana Jones Chronicles, and Quantum Leap (and maybe Dinosaurs). By comparison, this past fall offered Heroes, V, Eastwick, The Vampire Diaries, FlashForward, Supernatural, Smallville, Fringe, Medium, Ghost Whisperer, and Dollhouse.
Perhaps the market for such shows simply was never as big as some thought, or the market for such shows has radically compressed in recent years. Or... perhaps the folks who are attracted to shows like that are among the lesser valuable viewers -- folks who either are technically-inclined enough to skip commercials, or are perhaps supicious of advertising more so than the average person, either way resulting in the their eyes ending up offering much less value to advertisers.
Day One will eventually be broadcast, as a four hour mini-series. Who knows? Maybe it will be lucky enough to attract enough viewers to get picked up for a series of episodes after the mini-series. I hope so. I think, though, that the next few years are going to see a correction, with regard to genre programming. Perhaps cable will keep us flush with enough to feed our interest (none of the shows I listed above were cable programs). Given that "genre programming" generally includes science fiction, fantasy, and historical dramas, we've seen that premium cable is willing to feed the dragon (pardon the pun), with The Tudors, Deadwood, and Rome; not to mention True Blood, and Six Feet Under. And, of course, there is Syfy, offering three Stargate series, Battlestar Galactica and its sequel Caprica, Sanctuary, Eureka, Warehouse 13, Tin Man, Alice, etc.