Stillborn Franchise: The game was not well received enough to get work on a sequel going at a Sonic-level speed, and when Penders rose up in 2010 it put the kibosh on the plans for the RPG series.
Vapor Ware: The sequel, thanks to two main factors:
Screwed by the Lawyers: More famously we have the case against EA and Ken Penders, who went after them after being pointed out that the Dark Brotherhood were Expies of his Dark Legion from Archie Comics' Sonic the Hedgehog. Which started off his rampaging litigation into taking control back of virtually every character he created for the series.
Less famously, Bioware seems to have completely shut down any and all handheld development that isn't part of their Jade Empire series (which also seems to be Vapor Ware after four years of no updates).