I mostly play as a bounty hunter in open play. I sometimes see people and it does add an interesting question of what they'll do. However, it can also lead to some poor gameplay:
I tried a nav beacon in an anarchy system, there were a few humans, no one could make any bounty as you couldn't attack any NPCs as you spent the whole time being attacked by the other bounty hunters, despite having no cargo and no bounty for them to get. Sadly would have been better in solo play.
I also tried a conflict zone recently. I fought and killed the only human on the other side, then it was just an awful time of having other humans trying to steal the last shot and the kill. Again, would have been better in solo or group. They need to fix how kill rewards work to be based on % damage done.
I also met another human whilst in my standard bounty hunt in a resource site. I only had two fixed pulse lasers equipped because I prefer the challenge of fixed and I don't want to run out of ammo if it starts giving me cobras/anacondas to fight. The human sat at zero speed and just blasted me with auto gimballed weapons, the feds didn't seem to attack him and then I stupidly crashed into an asteroid. It annoyed me so much that someone so rubbish had managed to get me killed. I went back to fight him but he was gone.
I still play in open mode, but I think there's more chance of me being frustrated than having fun from it. I'm just looking forward to group play with shared bounties. Then me and my friends will go elite anaconda hunting.