That's what the Low class planets are for. They are planets, that for whatever reason (location, newly discovered, deadly, poisonous, war, whatever you can think of.) despite the fact that they are habitable class planets lack a substantial population. These planets are usually characterized by the lack of a night side. Ice and Volcanic are the only misleading ones as most of their population centers are underground and thus don't emit any light.
And Low Class planets suck for the most part. (I've been getting complaints on them from the SOGE forum. Which means they are doing their job.) They have little population, log slots, tac slots, and health. They even suck up money a bit. Most you can't get rid of it, but colonization lvls 1 and 2 you can get rid of it for the most part through upgrading the pop. (like ONE time and that's it) but 3 and 5... Well... they will be leaches on your income (somewhat) BUT all low planets have 2 more roids than their more civilized counterparts. Colonization lvl 4s don't get income hits because they are SUBSTANTIALLY more populous. Though I may hit the one or two little ones in there with a corresponding cash hit.
So I do have it in there just a bit differently.
(Oh and col class 5s are your MAJOR income planets. They suck, but they can't be beat in terms of crystal and metal roids. They have a -5 credit per sec hit that is always there. You can easily minimize it by grabbing any type of Industrial, High Terran, Urban, Rusty, or Ecumenopolis planet. Which are you major credit producing centers.)