1.) RO (to me that means RO, DH, MN etc..) is in the final months of existance so there's a limited player base.
2.) Maybe only 50% of the community realizes there are even mods for RO
3.) As with DH, MN is a seperate "game". If DH and MN could be incoorperated like the CC files were in RO, there'd be one "game" to play with all the extra content.
The only reason why DH has the few players it does is because of the 29thID and the few german realism units that can keep 2 or 3 servers populated. You will have some non-DH "clan" players that will pub and help fill up a server or two, but without the bodies to seed a server, it has no chance to fill. After 5pm est, DH has maybe 100 players at best, granted that's more than MN. If MN had a clan with 100+ members, I'm sure you'd see one server with players on it most of the day like you do with DH.
If all the mod teams worked with TW to make a final "RO Gold Edition" or something and combined all the RO content with all the mod conten into one complete package, that would be awesome. Box and sell it for $15 and for all current owners, have one major update to install all the files. Picture the awesomeness of one game with servers able to run RO, CC, DH and MN maps without having to make players startup a whole new game.
I for one hope to see all the mod teams move into HOS and continue their work as they were all great additions to the game and the community. Sad fact is they all came too late in the game to be appreciated enough.