I love this game!  Great amounts of fun, slowly amassing several fleets with which to wrecking-ball through the enemy (while they do the same to me, leading to scrambling to pin their armada down in one spot and devour them).  It is that process of accumulation which inspired a few ideas I developed at work today.  These would address a few of the issues mentioned by other posters, without adding buildings or waypoints.  Might be a pain to code, though... :D

No. 1 - All asteroids owned can rally all friends from adjacent asteroids by the push of a button over in the same window as the "Plant" button.  Asteroids hosting fleets of 100+ can reach two places out, and fleets of 200+ can reach three.  You might highlight the affected asteroids when hovering the mouse over the button.  This would expedite the mustering of a fleet, whether to attack or defend, without dragging eight different groups.

No. 2 - Fleets of 300+ intercept & drag into combat 1 out of every 3 foes traveling past their asteroid, fleets of 400 catch 2/3, and 500+ will catch everything.  These abilities could be aggregate for fleets adjacent to one another, so that a 300+ and a 400+ would catch everything passing between.  Thus, no walls or turrets needed.  Static defenses left behind on an asteroid would be a bit redundant when new fighters are spawned progressively as they are.

No. 3 - 500+, the maximum on any asteroid, and what I term an armada of its own, might continually bombard nearby enemy asteroids at little or no expense.  Not planet-killing stuff, but enough to whittle away at the enemy force.

That's my bid, anyway.  Nothing too drastic, appearance or concept-wise, but a few subtleties.  Thanks for making Dyson!