I finally figured out an explanation for why Vader was angry Admiral Ozzel came out of lightspeed “too close to the system” during the Imperial attack on Hoth.

If the Imperial Fleet ships were to simply hang back and wait for the Rebels to notice their presence, then they would be well-positioned to destroy any Rebel ships trying to flee the planet and escape into hyperspace.

But with the fleet in close proximity to the planet, then Rebels fleeing Echo Base have a chance of slipping through the blockade and getting into hyperspace before the Star Destroyers can turn around and give chase.

This might have worked as a means to mount a surprise attack, as Ozzel evidently hoped… but the Rebels had a shield generator that prevented making an attack from orbit, which the fleet commanders apparently didn’t know about until arriving at Hoth. At which point Vader orders a ground assault to take out the generator, which otherwise wouldn’t have been necessary.

So Vader’s original plan accounts for the possibility of a Rebel shield, saves Imperial lives, and also works to make sure more Rebels fall into the Imperial dragnet.