Galaxy creation leaves a lot to be desired after 0.65ish. I've yet to see more than 5-6 sectors on the second highest size and they're always connected like pearls on a string so there's a max of two substreams in any sector.
With 15 ai races that means that both exploration (you pretty much know how many races will be in each sector and since there's only five or six you can explore all of it very quickly) and expansion (given the close proximity sectors also fill up very quickly) are over super fast.
Essentially that makes it a 2x game instead of a 4x one which, to me at least, makes it uninteresting.