They're simply not working with it because it's not open source. The lack of, or bulk of, kaillera community has nothing to do with it.
As for having an online service that not many people seem interested in; have you tried to play arcade games on XBL or PSN lately? Take MK games for example, near impossible to get a decent online game that's in the same country as you (you can't even buy umk3 on xbl anymore). Kaillera now has a lot of the MK players from console merging over (plus p2p is better than most console netcode). Kaillera mame also has features you won't find anywhere else. Like 4 player 2v2 games (that's 4 players connected, 1 per character), in games like mvc and umk3.
Try the P2P version, you won't be disappointed. The only problem right now is that currently the waiting for games, and force port features are down (will be fixed soon). So you have to forward your port manually, and find the person you want to play with somewhere else (chat clients, forums, etc).
Finally, here's the problem with development of emulated arcade games with any netcode; most people's computers SUCK! Processor lag/frame skipping causes lag spikes. While they may be able to play these games offline perfect, online is a different story. This is one of the major reasons that 0.64 is the most popular mame for online. This is also why CS MAME will take quite a while to take off.
PS Hyperspin's hyperlaunch script could easily be modified to work with CS MAME.