No, you can't dock with it. No, destroying the shield generators does nothing. No, there's no "reward" for figuring out the secrets of the Nomad Citadel. Yes, waiting around in one spot and telling PVP-oriented people where you are will get you killed.
It's just there to look pretty. But a while back, I had a researcher character stationed on Sunderland just outside the Citadel. I had had planned a story in which he'd search through the Nomad ruins for anything at all that could help change the tide of the war with Kusari. It would have taken him all over Sirius to all sorts of interesting Nomad-places, and he'd be richer for the experience. And yet despite several strong leads that he came across in the beginning of his studies, he would have turned up nothing to help Bretonia's war effort.
Anyway, that's how the story would have gone, if I hadn't decided that I had too many characters going on and deleted him.
Point is, while the Nomad ruins do nothing in the game, they're far from "useless." Make something up and role-play it.