I've been trying to figure out why the Empire would send in AT-ATs to destroy the power generators when they could've just flown a few TIE Bombers in to do the job quickly. The AT ATs are landed some distance from the target (why?) and have to walk over to the base which wastes time and troops.
All I can figure is that Vader wanted a ground assault so that he could capture Luke. We can assume that he learned about Luke's existence and his last name in between ANH and ESB.
With that in mind, Vader already has interest in finding Luke...the question is why and for what? It isn't until later that he hears from Palpatine who also suddenly wants Luke captured. It's as if Palpatine didn't "sense" the son of Skywalker and the danger he posed until sometime after the Hoth incident. But Vader clearly had designs on his son before Palps ever realized the danger.
So, is that why Vader wanted a ground assault instead of just leveling the Rebel Base?