What’s the point of outposts and taking the time to setup supply lines and trade routes?
I have only done limited outpost building so far (just 2 outposts, and I haven't even linked them yet) but so far based on the buildings I can build there isn't much point. Once I have them properly linked it will basically give me a good source of 4 resources, but the only thing I need resources for is modifying weapons and my suit, and I can find or buy enough resources for the small number of times I upgrade weapons. So far I only switch to a new weapon and need to upgrade it every 10 levels or so.
The main need for lots of resources is... building more outposts. I assume that can eventually be quite a money maker, but I also already get plenty of money just from looting, so no need for that.
Now with that said, I haven't gotten the skill to unlock more buildings, so I would hope that other buildings that get unlocked allow you to do more interesting things. But the base no skill invested buildings seem to primarily be about extracting resources to use for further outpost building. I am hoping it eventually allows you access to unique benefits when you invest in the skill and heavily build up outposts. Like, maybe you can create and use some unique advanced ship modules you can research and build with a sufficiently advanced outpost.
But it may just be in the game for people that like doing that kind of thing. Which I kind of do like doing, so I could still appreciate that. If you don't enjoy that kind of thing, it looks like you can probably just skip it entirely.