If Open Mode truly offers to most compelling game experience, then that is where the bulk of the players will be.
I play in open and see the occasional human player. Given the vast size of the galaxy, it think the balance of human to NPC is fine.
I agree, I played in open all the way through beta & gamma, and rarely met other players but when I did I tried to chat (when chat was implemented of course), but rarely got a reply. I don't see that as a problem though I'm quite happy that it's this way because like the OP say's it's a big galaxy and that is how it should be.
On saying that it would be nice to be able to get in the same instance as players you've met in chat rooms or other forums. I know this is on the cards to be implemented (soon I hope) but if the OP is in a different part of the world, at present it is improbable you will be able to get together in game.