Well, I have absolutely no idea why nobody has offered that yet. The circuit is fairly easy to engineer. Possibly, because until recently there weren't those many devices with DVI-D inputs... Also, it's not trivial to tap the digital outputs from the FLI23xx (mechanically). The installation of the mod would be very tricky, trickier than SDI because of the number and type of pins and signals involved.
What really irritates me is that the manufacturers are delaying introduction of DVI-D outputs on their players for no apparent reason. For them adding DVI-D is absolutely and completely trivial. Before they had the copy protection excuse (no Macrovision), but now, with HDCP (and with off-the-shelf DVI-D HDCP transmitters available), not even that serves as an excuse anymore. Heck, I could change the design of the 963SA to have a DVI-D HDCP output in about 10 minutes, including the layout changes on the PCB CAD.