I'll have to grant that Threepio has the ability to rise to the occasion. This one, however, is compounded by being a plan that works, not because it's so clever, but because the story needs it to.

What if these well-armed stormtroopers had simply blasted away like they did in ESB? The seven or eight troops that rush off to get the droids look clumsy and almost blind. Then they are overpowered by the ewoks so completely that they seem comical. The officer that orders them to their deaths is another almost comical element. Overall, this little sequence contains a lot of what went wrong in ROTJ. Taking it out is like removing a sore tooth-- and it lifts right out because the ewoks sound the call to battle as soon as it's over. The call-to-arms triggers a much more powerful image of ewoks rising out of the forest all around the troops. It's not even clear what use it was to have Threepio jeopardize himself when it only distracted a handful of soldiers.