I don't see why it's unfair that your world maps aren't automatically shared. That's how most games work. If you want them shared, just use the cartography table. If you don't like your players going off on their own, then you should have told them you want to go with them. Though it's strange you find this a problem in the first place. I have 9 players on my dedicated server. I don't care whether they share their world maps or not. Of course that's just me.

Also, the game is in Early Access. The IronGate roadmap states the they will look into multiplayer options later in development.