Against strike craft I see two things :
1) Other strike craft that is able to destroy carriers
2) Mines thats destroy strike craft
Anyway TEC possess a lot of abilities to shoot down strike craft : hangar flak (one shoot destroys one vasari fighter), Kol ,Dunov,Akkan (armistice) and strike craft. Vasari possess Kortul devastator that make strike craft useless.
Advent have their own strike craft mainly to fight strike craft. (I found TEC more versatile than other nations)
And starbases could possess something like 14 squadrons then it's enough to kill carrier also/defend against bombers.
I guess strike craft is not so unbalanced but player should be prepared to face it from start of the game (build only fighter, starbases with fighter, aso).
But what happen if opponent doesn't use strike craft but instead marza power..
or novalith cannon?..