[PvK]

Troops just need a cockpit to give a happiness bonus. But they're nearly useless as troops then, of course.

Drones are cheaper than ships because purchase price is only a small part of a ship's cost - the maintenance cost is what makes a fleet expensive, and drones cost zero. Therefore they are very cost-effective for peacetime build-ups. They also have several other advantages, which have been described on other threads (speed, damage, to-hit, concealment, no happiness penalty for losing them, etc.). Low-tech drones may be easy to shoot down by themselves, but high-tech drones in hordes or combined with other forces can suddenly become a very serious threat.

However you and everyone else is right that they would be a lot better with a "move to" order!

PvK