[Normati]

It might not be practical to send information as light. You'd need a powerful transmitter so your signal can be detected among the noise from stars. It might turn out that sending a spaceship is actually cheaper and just about as fast. The spaceship can steer itself and doesn't spread out the further it goes.

[sanxiyn]

I think galactic civilization will either solve noise problem or install enough repeaters if that's cheaper. Repeater network will have enormous fixed cost, but I don't think its variable cost will be higher than spaceships.