Believe it or not but response time between a few players can be actually better with P2P, because it's a direct connection between the player's machines. Otherwise each manoeuvre, each shot and each touch to another ship would require an additional stage - the central server. What the servers in ED do - in simplified terms - is to broker between decent connections. It's getting tricky with oversee connections and greater number of players in one instance, but that would be even much worse if everything (mostly collision detection is the delicate factor here) would have to pass a central server. The limitation of light speed is actually a thing when it comes to connections that are further away than 1000km with signal that have to go back an force and even have to be calculated in the middle.
Just saw my previous speaker actually mentioned EVE and, yeah, Jumpgate and pretty much answered the question from another angle.