Speaking with Japanese gaming magazine Famitsu, Masaki Sakari of porting studio 5pb noted that the rejection of those titles—ports of Cave's Dodonpachi Daioujou Black Label X and Ketsui X—prompted a move to a more traditional retail release.
"They rejected all of our proposals saying, 'We are going to cut down faithful arcade ports,'" said Sakari. "We felt so frustrated. We wanted to show them that their decision was wrong. So we switched our two most promising projects into retail."
Despite the recent release of Warashi's Triggerheart Exelica and the upcoming edition of Treasure's Ikaruga on XBLA--both arcade shooters--the shift most likely represents Microsoft's desire to move away from the recent flood of straight ports that have hit the platform, many of which were developed by Backbone Entertainment for a number of different publishers.
That said, recent releases show that Microsoft clearly has no qualms approving reimagined or enhanced versions of existing franchises, such as Mr. Driller Online and Bionic Commando Rearmed, for an Xbox Live Arcade release.