Refinery has a simple body influence. Not every system allows refinery but simple rocky bodies are very common. I'm not sure we need a refinery orbital installation more than we need a way to create an agriculture station without other influences or high tech orbital with L pads.
Not every system has to be good at everything as long as everything is possible. I don't currently like how the single sun systems are but we choose them and I've now learnt not to choose themI have a system with only one sun and an asteroid belt. Then all have to be orbital. I would like to get more from those asteroids.
Colonization is to make max out of every resource you have. With little you have to benefit from everything. Besides orbital refinery makes just as much sense as orbital mining.Not every system has to be good at everything as long as everything is possible. I don't currently like how the single sun systems are but we choose them and I've now learnt not to choose them