Picard made the Borg creepy and menacing again after their overuse.

Also kind ol' grandpa Picard is wonderful

The Borg was a brilliant idea. Not new, mainly a variation of grey goo theory, but brilliant. A... species?...that was nothing except assimilated life forms from across the known galaxy. Hive minded and collecting the full knowledge of every sentient species who's individuality..

..they pilfered. The ultimate colonialists. But without even any real monarch to focus on, no center of gov't. British Empire meets decentralized bitorrent.

No idea what they knew and so disinterested in inferiority that they would let you walk on their ships unless you...

...became sufficiently 'interesting'.

[CW rape, rape imagery]
They also are personifications of...the R word and patriarchal power structures. They take you and your body, without consent. Violate you and force you to comply. And they're so powerful...

...you have no reason to believe you'll ever be saved before your very soul is ripped out. They are pure evil, and the end result of the idea of "pure logical pragmatism" that Vulcans originally were supposed to skewer but too many people failed to get the memo.

And all this amplified immensely by just how mysterious they were. No one knew where they came from.

No one knew how they started. They probably know, but would literally never tell you or shed it because it made no difference and those qubits were better spent elsewhere.

They were menacing and creepy to an extent that series rarely was, generally being very sanitized and utopic.

Then they were overused.

They became the villainous sonic screwdriver. And they kept adding to them in ways that lessened the creepiness. The Queen...

...provided an avatar villain to make them more easy to engage in conversation. Meaning they started being written as villains you could talk to. Snidely Whiplashing the unknowable creeping colonial, unemotional plunderers and rapists.

It flattened them.

I'm not yet finished Picard, a couple eps remain. I also never read any licensed books or anything. But the fact the series is treating them as this unknowably vast creepy thing again, the "Artifact", its impact on the survivors, etc, makes them so much more mythically awful...

...than they've been in years.