TIE Advanced fighters were only produced in a very limited supply; TIE Defenders were invented for the "TIE Fighter" game since players were used to flying shielded Rebel starfighters. I think it's safe to say that any Imperial fighters not seen in the movies were pretty darned uncommon in the Imperial Navy.
A single starfighter that can blow away anything in space isn't really the Empire's style, either. Their philosophy relied on two main elements: First, big is good; and second, if you must build small things, build a crapload of them. TIE/D's aren't really conducive to either philosophy--but Imperial Star Destroyers and TIE/F's sure are.
The Rebels should be heavily reliant on fighters at all tech levels, since their philosophy is to get high-quality small ships that can slip through the Empire's large-scale defenses. They had more carriers than cruisers or destroyers for exactly that reason. EaW never fully captured the Rebels' focus on starfighters, thanks to the incredible effectiveness of the Tartan. I'd be very much in favor of boosting the Rebel fighters' abilities against capital ships and reducing the effectiveness of the Tartan--since the Tartan plugs the hole in Imperial defenses that we all know was left gaping wide open!