VOY simply didn't have the resources DS9 did when it came to maintaining villains as super-tough invincible enemies. That's also why none of the other villains met their "potential", because meeting said potential required doing stuff that a single ship on its own couldn't survive.
DS9 didn't have any "super-tough invincible enemies." Not one, ever.
They had
tough enemies. Enemies that were believable as credible threats, and never lost that status. But Jem'Hadar were hardly unstoppable. That's all I (and many others) would have asked from the Borg on VOY. They don't need to be invincible, just not "lolborg", which they became.
And why must the effectiveness of these adversaries be based SOLELY on how badly they can knock the ship around? Everything in the paragraph I quoted relates to how Voyager's hands were tied when it came to villains because of how they couldn't blow up the ship. What about the fact that the Romulans from TOS (the Klingons, not so much; they were pretty simplistic, I'll grant) and TNG, the Borg in TNG, the Dominion in DS9... these were
more than just bad guys to shoot at. They were
interesting, for reasons beyond their ability to blow up our heroes ships.
That is the problem with the Kazon.
As for the Borg...
RyuRoots makes a good point (that I hadn't even thought to bring up) that they could have just not used the Borg so much in the first place. But if you ARE going to use them a lot, there is a middle ground between "they are invincible and will blow up our ship" and "we can beat them easily." Voyager, in later seasons, was fighting off Borg ships like they were any other ordinary adversary. Hell, Janeway at one point decided to
hunt Borg ships for resources. This is DUMB when the Borg were supposed to be pretty much the biggest threat in straight combat. So have Voyager survive WITHOUT beating them in straight combat! TNG did it all the time (and before you bring this defense up again, no, it had nothing to do with falling back on being in Federation territory. The Federation armada in BoBW got its ass kicked, so that made no difference). In BoBW, no one could stop the Borg ship in straight combat. The E-D crew ended up beating them through technical trickery and guile. In First Contact, a fleet of Starfleet ships (one that was made up of far newer and more combat capable ships than the BoBW fleet)
barely managed to take the thing out JUST as it was reaching Earth (and even then, Picard used his intimate knowledge of the Borg to pinpoint a weakness; hard to say if Starfleet would have won without that). In "I, Borg", they hid from the Borg ship that came for Hugh so they wouldn't
have to fight it. Yet we have Voyager fighting off Borg ships left and right, and beating them with the Delta Flyer.
Which, again, was because DS9 was able to offer up plenty of non-main character ships and personnel for the Jem'Hadar to kill off with impunity or simply had them both fighting together against a third opponent. Or they explored the character of the Jem'Hadar without them being an adversary at all.
NONE of which could be replicated with the Borg in VOY. Or ANY of the villains in VOY, frankly.
I have one major example to counter this. And that example is... Voyager! Specifically, "Scorpion". That was
brilliant. One of the best 2-parters in all of Trek. And the Borg were handled perfectly. They were menacing, threatening, and scary as ever,
despite the fact that Species 8472 was tearing them apart (which was, in and of itself, a great twist). It was made very clear throughout both eps that fighting even one cube would be a really really bad thing (so they didn't. They found other ways to deal with the problem). They even did what you said DS9 did, only in a MUCH bigger way (Sisko and crew only teamed up with Jem'Hadar once, and that was just to fight alongside Jem'Hadar against
other Jem'Hadar, and was a far less epic episode than Scorpion was): they teamed up with the Borg to deal with Species 8472. Of course, this was later revealed to be a mistake, and in the end, there were no easy answers because the fact of the matter was that both the Borg AND Species 8472 represented serious threats to the galaxy. That's what made this ep great! It's not just about villains that can beat the crap out of you, it's about villains that are
interesting to watch. You keep saying Voyager couldn't do this. Well, in Scorpion, Voyager DID it, with TWO villains at once, as well as Trek has ever done villains.
So what happened? Why couldn't they do what they had already done with the Borg? Why couldn't the Viidians and Species 8472 - both of whom started out as interesting, fantastic villains -
stay interesting?
This is the biggest shame to me about Voyager in general. I can't just write the whole series off and say "It sucked" because it had moments of greatness. The writing was just so damned inconsistent.
As for Seven, there was that in-show justification that she needed the suit to continually regenerate from borg implants that couldn't be removed. So there was some handwaving about it.
Bwa? I don't remember that at all. Which ep was that in?
And hell, the pretty sci-fi babe in a strange outfit has been a staple of sci-fi for so long, Trek shouldn't be called on it anymore than anyone else.
I'm
not calling Trek out on it more than I would call out anyone else. This "staple" is an archaic, stupid, offensive tradition that would be best completely done away with. Any other sci-fi that is guilty of the same thing with a character like Seven (or Troi) would earn my criticism to the same degree.