A sheriff needs a deputy. A PC needs a subordinate to relay orders.
Who else are you going to blame if things go pear-shaped and you don't have a handy NPC deputy nearby?
Admiral Ackbar: The Lost Orb is a honeypot. We can't afford to get entangled in it. If we're tempted by the enticement we may fail our mission.
Admiral Ackbar: Fighters, attack formation stratagem!
Arvel Crynyd: Green leader, forming up position.
Admiral Ackbar: We'll use a feint gambit to hook them into our plot.
Arvel Crynyd: Right. Let's do this for Dib. This is the most exciting thing since I was thawed out.
R2-D2: Why is Ackbar giving orders? I thought I was in charge.
Admiral Ackbar: Yes, but your communication is collared. You need a local deputy to implement your machinations.
R2-D2: So. I finally get to control another giant space battle. And it's via 300 baud uplink from the ground.
R2-D2: No. This is awesome.