I think the empire's reliance on droids do make sense. They utilize mechanical terrors to make people submit to their power, be it through AT-ATs, Super Star Destroyers, the Death Star, or even Darth Vader himself (he's more machine than man, you know). Vader himself does criticize high command for their reliance on technology over the force, while the emperor seems to like the development of terrible technologies as a mean to cause suffering to others.