To address the Lucas comment, to be honest this is one point the story makes zero realistic sense in. And its not just Lucas, in the Force Awakens its the same. The Empire, despite having clear advantage and much better technology, gets wiped out by a much smaller force. Well the directors & Lucas want to make a political/ideological point (that no matter what, the evil side is flawed even with all the power, and can never win).
On the game side, tbh, I am quite interested in how Empire fares now. That Vader Zeta ability seems SICK. And there are some potentially very strong Empire characters like Tie Fighter Pilot, but need to be placed in teams strategically otherwise they wont be strong.
And fully agree that there are not enough Empire characters. Sith are enough though, as there were never many Siths to begin with (in the Palpatine timeline).