What's the reason for hexagonal systems?

[Tickwick]

The whole point of using hexagonal shapes instead of squares for example, is to pack as many adjacent elements as possible within a small area, but if you look at the map you see there are huge empty spaces between systems with no reason whatsoever.

Am I missing something?

[Sentinel-Ghost]

Leaves room to add more systems to the Universe I would imagine.

[Tomonor]

Look more futuristic too.