If your in an active enough alliance which use discord then you have the ability to stop so called big fish attacks especially with moons and careful planning making sure an ally is nearby most of your planets. You can ACS defend if there are a few small fish especially with jump gates.
For me the game needs a method of more strategy in attacks rather than the bigger fleet wins.
For example certain ships are exposed depending on the planets temperatures, maybe add in atmosphere density which effects fire rates, maybe have bonus strengths and weaknesses depending on the time of day you attacks.
Give more features to defences
All examples of course. It does get a little dry especially in older universes