I'm unsure how there can be a "Borg Queen" in what we had known previously about "the Borg" before Star Trek: First Contact.
Initially, The Borg were in a cube with however many tens-to-hundreds of thousands of drones operating it, none more important than the other. One could even apply a social commentary of communism in the Borg. It had no heirarchal weakness, you could take out the upper-right quadrant and the rest would just adapt and rebuild, and Q stated when set up the Federation's "introduction" to them. Immediate, synced reaction and decisions in a split-second notice.
Then, we have a Queen, who makes decisions and commands drones to do what she wants, which sometimes isn't even based on logic or data, but for personal reasons.
Once the queen was introduced, it made for an interesting Data vs. Queen confrontation and story, but it completely cut the balls off of what was so coldly threatening about the Borg.