[Suicide Junkie]

The problem with weapons is that you have to get in range to use them.

Yes, an invasion force will lose a few ships at a warppoint, but the rest are free to roam and retreat everywhere else in deep space.
Posting a satellite in every hex to prevent retreats and replacing them every time a ship flies past is not fun.

And my point is that, as is, they do not have to be designed to run the defenses. Equal speed ships... in fact identical warships to yours can escape with minor losses.
You can never catch up to them, so if you use max range strategy you kill at most one ship during the chase to infinity phase. Point blank attempts depend on your starting position, but they are firing back at you with just as much firepower as you are at them, so any of your ships in range get shot down, and maybe you can take some with you.
Suckage ensues.