Why do you let your enemy get more than two spaceports in the first place?
If you give your opponent time to collect enough ore and do the research and build the spaceports, then in reality, you also should have got that amount of ore, If you are plymouht you could build spaceports yourself, if eden, you could build meteor defence, and still have lots of ore left over to build acid cloud, thors and EMP tiger weaponary.
I don't see any problems, eden has greater firepower and plymouth greater defence/disabling ability, in a long game!
Stop your whining and learn to play the game strategically
Missile spamming? Thats not spam its a tactic, that only happens because you let it!