What about the Borg losing to the 8472 aliens, was that "wrong" as well?
8472 has to be a part of the big picture. Using the reported stardates I come up with this time line and in this chronological order, all happening within a three to four week period.
The Borg under Queen 1 encountered Species 8472.
Queen 1 decides to attack the Federation (First Contact
) fails and dies.
Queen 2 is chosen or coroneted or whatever, but the key here is we are dealing with a Queen who is new to individuality and suddenly confronting a Species that they couldn't assimilate.
Queen 2 sends Seven of Nine to Voyager to get the "weapon" to defeat 8472. I don't believe that the Borg entertained the idea of really letting Voyager go for even a second, and I believe Janeway knew this.
Voyager escaped and in that escape separated Seven of Nine from the collective. I don't think it was an exaggeration when the Queen identifies Seven of Nine as her favorite. So we have much more than fear at work, we have jealousy and anger at work too.
Now skip ahead 18 months and you get to Dark Frontier
. Now the Queen has had some time to think about what has happened. The mechanical or technological parts of the Collective can't do this, it's why they need the Queen.
So what has she got to think about? Well, Species 8472 is still at large and still unassimilateable, and what is worse they have opened some kind of dialogue with Janeway. She has had access to the memories of Enterprise's crew from First Contact
and now she has to know now (if not before) that there is a species named Q that interacts with members of the Federation. They also know by now that the Alpha and Beta quadrant harbor the Organians, the Wormhole aliens and they probably know that something called "The Dominion" is claiming a lot of space in the Gamma Quadrant. All species that exhibit great power, but who are in all likelihood unassimilateable.
If she isn't scared she should be. She has to produce perfection and if she doesn't she can be replaced as she was after her failure at Unimatrix Zero
There has to be some emotional factor to explain why they do what they do, if not then you have blown Star Trek's concept away, and completely reversed everything in David Mack's Destiny