Ignoring the idea of tactical location (i.e. the colony itself is not economically viable but is needed as a refeuling depot or watch station or something like that in a key area of space), I could see ice planets being used to get lots of fuseable hydrogen, while volcanics and asteroids hold a lot of mineral wealth.

Well - logically if you'd want to settle an outpost on or near them the only reasons would be 1) overpopulation on a nearby world 2) need for resources found on the planet 3) prison colony 4) strategic location 5) escaping from nearby world

And - if there was any population on those planets, you would - 1) exterminate 2) absorb 3) leave them be and see what happens.