We have had a DarkRP server probably around half a dozen times over the years. They start out strong for about a month or so then they slowly waste away until they are perennially empty.
We don't really have the type of player base to support a RP server, someday we might have enough interest in it but we would practically have to open up a sub-branch of RND to support it. As a good RP server requires a serious amount of time investment and maintenance on the part of the administrators, in order to keep things running smoothly and differentiate it enough from the other servers.
I would personally rather have a space-build if a version ever comes out that doesn't crash every 15 min.