which has always been really stupid. I mean, why wouldn’t the force field block a generic energy weapon or literal projectile, especially during what was already a hostile situation?
It's just always the way they've worked. They do things that at first seem illogical to us, but are part of their methodology.
It works out pretty well for them. They literally don't care about individual drones and happily sacrifice them willy-nilly.
Q even says the first Borg to visit the Enterprise is just there to "gather information."
Heck, why do the Borg ignore hostile invaders on their own ships until they are directly attacked?
It's just how they do things. Singular, focused. Not thinking outside the box, but overwhelming their opponents with force when the time comes.
Why did that first cube let the Enterprise blast it to pieces at first? They probably could have stopped it. But they didn't. They learned from it, regenerated, and came back stronger later with the knowledge they then needed to be unstoppable.
By the same token, it's perfectly fine to let a drone or two get blasted by a machine gun. Because that will never happen again.
It's just how they do things. It's strange. It's alien. It's supposed to strike us as odd and counterintuitive until we realize that they've just been gathering info the whole time to then come back and completely kick our asses.
Not to mention that the borg shields seem to work the exact opposite way other force fields do in Star Trek: usually you have to modulate a beam (or torpedo…somehow!) at a precise frequency to get trough, the borg personal shields don’t protect from anything they are already prepared to protect from for some reason.
Actually, that's not how shields work in Trek. That's how you "cheat", like in "Generations", but the vast majority of the time, people aren't attacking by sussing out the specific shield frequency and shooting through them.
They just pound and pound on "raised shields" until they eventually weaken and fall.
And there's nothing inconsistent about what we've seen with the Borg. They literally let themselves get shot so they can learn about the weapons their enemies are using. Note we've never seen a Borg shield go up that DIDN'T work. The shields only activate once they've figured out how to stop them.