Actually a lot of people have asked for this feature in some form or the other over the years, the second most after boats. (And before trains)
Explanation could be trivial though: Allows you to make your own local government, showing the middle finger to former global government which seems to be something commonly liked by existing players, where trains is more something new players would like to see.
Nontheless, settlements feature (or very early Multi-Government, then Towns & Nations) was planned since the start of development of Eco, so it's not based on player requests, but was part of the game vision all along. (And will be extended even further)
The system changes the core gameplay of Eco (intendedly so) quite notably, by the way. So every server will ultimately use it, which means every player outside of singleplayer does, with the occasional purists. It's actually the biggest change to Eco's core gameplay since I work here, which is five years. It's no longer about having "use" for it (which is the whole point we did this), but being a core part of gameplay for everyone. (So it's no longer something you may have use for, but something you need)
I fully get the rant, but as usual in game development singular people are always missing the whole picture, as they do neither have access to the data nor the full plans for the game. It's yet another part of Eco Infinite, after all and links the civic system that was for many people an oddly outstanding thing a required part of gameplay, incentivizing collaboration massively even further. And the occasional bit of political PvP with the annexations.
So where there was no use until now, there now is one for everyone. And that's the whole point, next to the gameplay implications that it has. Keep in mind Eco didn't want to be some random sandbox. Players founding their local settlements, getting hands on geographically limited resources, dealing with how they will take that advantage and deal with others is all part of the Tragedy of the Commons, just as resource shortages. Players, as always, decide themselves on if and how all players on the same server can have the most fun by their behaviour and collaboration - or not, and just annexing whatever they can. Failing due to missing cooperation or noone stepping up to get stuff sorted locally and helping others out is a intended and not rare part of Eco. It's up to every single player on the server to not only care about themselves, but everyone if they want to maximize their success. Has a bit of real life, eh?