https://www.youtube.com/watch?v=JRFVEReJ4Kg

This mission stood out the most for me when playing Starcraft. A mission from the original SC which pities you with a small task force on a forgotten space station trying to find Tassadar and Raynor without waking up the entirety of the zerg base.
Plus Starcraft 1 maps always had a simplicity to them compared to the Brood War campaigns which tried very hard to make it more scripted and similar to a Red Alert 2 campaign.

I wonder how the concept would be handled now with a more powerful editor and engine.
Or rather how would have the Blizzard team behind Brood War handled some of the SC Original maps.

I'm quite certain the team behind BW is the same behind the original SC (ie they handled it the same). You can easily tell that both games have the same theme in their campaigns, which is mostly just to destroy all enemy buildings. That was the mission objective of like 70% of the missions. Now, if you're talking about how non-affiliated mappers such as us could handle it, that's a different story. I'm sure anyone who knows how to use Scmdraft could make a more interesting version. You should give it a try.

Yeah, SCBW has poor design intrinsic to every map, even considering the limitations of the engine. It's pretty obvious that Blizzard didn't actually try.

Anyone can make better campaigns than Blizzard's own. Go for it. If you need help, ask.