VADER: The Rebels are alerted to our presence. Admiral Ozzel came out of light-speed too close to the system.
VEERS: He felt surprise was wiser...
VADER: He is as clumsy as he is stupid. General, prepare your troops for a surface attack.
Even if Admiral Ozzel came out of light-speed at an optimal distance from the system, how did they plan to approach (land to capture Luke Skywalker) Hoth without alerting the Rebels?
Also, didn't Darth Vader's ultimate plan to capture Luke Skywalker on Hoth require a surface attack anyway?