Except the Klingons, Romulans, and Cardassians were individual characters, so there was a lot more diversity in what they could do with them. You could have good guys, bad guys, characters who had specific desires, characters who were the perfect examples of their culture, and characters who went against their culture. You couldn't have any of that with the original Borg.
The original Borg could have worked as a one or two appearance thing, but after that things probably would have started to get repetitive.
Which would be a really good point, except that the Borg only had four appearances in all of TNG and their appearance in "Descent" is EXACTLY the kind of variation of the "mix things up" variety you describe.
The divergence from the Q Who pattern was primarily introduced by First Contact and Voyager was forced to abide by that in
Scorpion. And First Contact was the first and only big-screen treatment of the Borg in the entire franchise.
It's really not as if the Q Who premise was actually in danger of BECOMING repetitive. They abandoned it long before it had a chance to do so.
IMO enemies are a lot more interesting when they are people who our heroes can interact with. Sure mindless monsters can be fun every now and then
Yes, they certainly can. And that is a storytelling niche in which the Borg would have excelled.
TOS had no fear of Space Monster plotlines; they gave us the Doomsday Machine, the Space Amoeba and the Cloud creature, and IMO those episodes are still quite entertaining. TNG had its Crystal Entity (twice), Neguilum, whatever it was that tried to eat them in "Time Squared" and the ravioli creature in Galaxy's Child. Voyager, too, had its space monster stories once or twice per season.
Casting the Borg in that role has potential to simplify the writing and content of that theme if and when it comes up in an episode. They're a known quantity, so a viewer doesn't have to waste energy wondering who/what the Big Bad is and what it's after and can instead focus on the "How the hell are they going to get out of THIS one?" aspect of the story.
As good as Alien and Aliens are, they just wouldn't work as a regular TV series unless there was a lot more to them than just Xenomorphs attacking ships and colonies.
Which, again, is why I brought up
Alien: Isolation. That's a game and a narrative that takes a good twelve hours to play through even if you're playing it on easy mode, because there's a lot of OTHER shit going on that the characters also have to deal with. Personalized enemies too, in the form of the paranoid armed gangs that have taken over the station now that all the authority figures have been eaten by the Xenomorph and impersonalized enemies in the form of crazy androids, security systems, and of course, the xenomorph itself. Would an episode that included both a devastating Borg attack and a Klingon general trying to exploit the situation for his own gain REALLY require the personalization of the Borg? For that matter, a story about a group of survivors on a space colony that has been wrecked by a Borg attack, struggling to survive as social order collapsed around them? Hell, you could rewrite "Silicon Avatar" and replace the crystal entity with a Borg Cube and it would still work just as well, but ONLY in the original Q Who paradigm.
And yes, the entire concept of the Alien franchise becomes meaningless when you deliberately oversimplify it to "alien attack on ships and colonies." But if you're such a crappy writer that you can't come up with a descent story for an Alien title, you're probably in the wrong industry.
I can't help but feel that the "faceless hivemind is too limited" theory is really just an argument from lack of imagination.