Day one the starter area is going to look terrible just from people testing out the editor tools. It's going to be a real problem. It has been in every single "builder" game I have ever seen tbh. I actually just started a post about this very topic before I found this one.
Frankly, there's basically no way people are all going to be conscientious about keeping the planets looking aesthetically pleasing, that doesn't even take into consideration people who legitimately enjoy trashed landscapes. People just go the path of least resistance because we're all inherently lazy. Tearing stuff up and moving on rather than taking any time to repair the land, or heaven forbid being careful not to tear everything up in the first place, lol.
The devs will certainly need to come up with some way to make sure it's not a problem, at the very least the starter planet and the ones closest to it. Otherwise before very long at all the new player experience is really going to suffer. The idea that you can always move further from the center if you want to find somewhere that looks nice is a bit short sighted. Sure, you can, if you're an established player with the resources to do so. New players don't have that ability though. They are left with the wastelands left to them by previous players.
On top of that, at some point people will just get too far apart and no longer interact with each other. You see that a ton as well. Even down to small ecosystems like a minecraft server. People move out really far from the center in order to find some security and a nice looking place to build. Soon everyone is so far apart it's too much trouble getting to each other anymore. In a game like DU, people are going to naturally stay closer to each other due to markets and trading. So more likely than moving really far out to live, they will colonize near the markets and then move out to mine, bringing the resources back to their more centrally located bases. This will create a large dead zone around the markets of fairly trashed planets. You'll then have to move even farther out to find resources and it just increases the time sink. I'm sure this is where warp gates will come into play, but really, depending on how that whole system works all you're doing is buying a temporary reprieve each time to make a gate. People will colonize near the gate for ease of travel and then lay waste to a ring around it.