To me it's supposed to indicate to the audience that stormtroopers are all over Endor, hence the rebels are walking into a really dangerous place - which increases the drama, (as does the fact the stormtrooper watches the shuttle land somewhere clearly off the beaten track and not where Imperial troops would have landed). It also hints at the idea that the Empire know that all about the rebel mission - something later confirmed by the Emperor.

It also works because it has a cinematic quality and scale to it which ROTJ largely lacked... and is mostly why I like it.