Yeah, collecting the parts is
on some level justified in the script. Isn't there dialogue specifying that the Kolarans are at an 'industrial age' level of development? Certainly they've got land vehicles figured out, so leaving B-4 there for them to uncover could result in them accumulating technological advancement centuries ahead of their time. I think what rankles with me about the sequence isn't so much Picard acting so out-of-character in wanting to trawl over the surface of a planet in a Jeep in the first place, but more the scenes where they open fire on the Kolarans that are attacking them. Sure they're under attack, sure maybe Worf went for non-lethal takedowns or something, but it's just like..... that's
what makes it such a violation of the Prime Directive. What if
they *did* kill some of them? Even by accident?
To be honest I think I'd have found the entire scene more acceptable if the action sequence was excised. Keep Picard, Data and Worf looking for parts down on the planet in their little dune buggy, but cut the following scene where they get into a fire-fight with the locals.