Originally Posted by Naso
But there were tons of factories that were destroyed by Zaarin, and so they had to match his tie-d's and kept even most of the avengers off the front lines. Just avengers would have evened it a lot. If they hadn't been learning, they wouldn't have even developed those, let alone gunboats.
They tried to match his Tie Defenders by having the Missile Boat.
Gunboats were mainly used for tactics requiring a small hyperspace capable starfighter. It has nothing to do with having a ship equally strong or better then the Rebels. In fact, the Gunboat was barely more then a Y-Wing on steroids.
Avengers were simply based off the Tie x1 idea but remained marginal in its use.
All in all, most of those crafts were too expensive for serious mass production and mass deployment, which is against Imperial philosophy.