Welcome to private server life. This is eventually what happens now that we don't have newcomers every so often. It's become more like a museum than an actual server, including the not nearly as many people aspect. Sure we don't have to deal with grief (as much) anymore, but we've lost the need to moniter the server if there isn't someone else already on.
I for one have grown tired of logging on and not seeing anyone, so I've taken to hanging out elsewhere. Sure, Unobtainium is just as epic and awesome as ever, but it's grown quite boring without new people joining or the need to moniter people. Although the rare times I've logged on and someone else has been on is always fun, it doesn't happen enough for me to constantly stay logged on.
I bet if we switched it back to public for at least a little while, you'd certainly see someone if you logged on. There will of course be the matter of grief as well, but it's to be expected. It keeps us on our toes and actually on the server to try and stop it.
There you go, my thoughts on the matter.