that area has 6 players around it, so even though it seems huge, it's just a little bit for everyone. it seems like for you that was the only area you could really expand into.
in general, the world creation code checks how many outposts each player would get with optimal expansion, and if the gap between the best and worst players' outpost counts is 4 or more, it discards that world and creates a new one.
most of the time the gap between the best and worst starting positions is 0 or 2 outposts, and that's something that can change based on how many drillers you send where.
overall, your world looks ok to me in terms of starting positions.