Well now they do.
I had to take creative license with the set Null. I based the concept for the Rebel walker on something that would resemeble an early designed Imperial AT AT. The idea being that the rebels could not build new ones to combat the Imperial walkers so they bought the older ones and upgraded them.
No where is it written in stone that the Rebels cannot have AT-AT's. The rebels are a mobile force so ya it stands to reason they would want to keep defenses small and portable, however SE IV is NOT the Star Wars universe. In SE IV the Rebellion has to protect the planets its colonizes.
If your looking for a true Star Wars game that follows the connon literal, by the book, God graceful line of Lucas and the Star Wars fanatic fan base, then go buy Rebellion or wait for A Galaxy At War to come out, in the mean time just enjoy the set. You can always change things to your liking or make new images to use.
