Because you can get it as your first perk, by the time you have repeatables the influence it will have saved you is enough to have conquered half the galaxy. And since wide is taller than tall that is a big deal.
Well it's mostly usefull for building new starbases, so very early on. Conquering other empires is a midgame thing anyway, unless you use purification/hunger/etc. Conquering others early is only viable option for purger type empires. And for purger type empires, you don't need this perk so w/e.