Probably just a lack of intrest and time on the behalf of those with the talent to do it.
And a lack of talent on the behalf of those intrested with time to do it.
I'm in the latter category... and I think only Descent II had the Direct3D coding in, so it would be the better one to port, but as I said I'm useless so there's not much point in me doing anything but wishing the day away on it.
