Why are non-rebel and empire characters in Rebel Assault?

Mephisto_style

I am just curious.
I mean, I am grateful I can use my Resistance arena team to auto through a 6 part battle, but Rebel vs. Empire is like 35 years before FO vs. Resistance.

TekkarEdorf

Because it would be really dull if you could only use Rebel/Empire to do 4 combat missions, a special mission etc.