Orbital Refineries

Is it just me or do orbitral refineries not seem worth it. They cost 20k CO and take up a unit slot that could otherwise be used for another warship. Since they can only be built on colonies, they don't usually see a return on investment until 16-ish days, because Terran planets only put out about 500 base CO. Water planets are a little better, but it still seems like a meager bonus, except perhaps on a home world, and if ships slots are at a premium, it would not be prudent to build them on all of our colonies.

Am I missing something or are they just marginally beneficial?

Well, as a Warlord, I know RO is like Water to a man in the desert, so even 2% increase is enough of a reason to build them for me.

I just discovered that the RO skill is one of the most important in game. Maxing it is important to survival. (Unless you're a trader)