In my head the justification for all of that is that the queen arose as a necessity to have a single individual for the crew of the Enterprise to interact with. This required her to have a certain amount of autonomy from the collective consciousness, the end result was that she turned into a bit of a dictator and because she had control over the collective she essentially took over without much fight. This would have been obvious to anyone else that this was a possibility, but the Borg had no experience of individuality in the collective before that, so the concern never occurred to them.
Eventually she died and the collective were released from her, and now they are back to being a hive mind. A hive mind that has learned not to do that again.
The reason seven of nine did not become like that was because the queen knew that that was a possibility, and so kept her largely connected so she could to a large extent control her.
I kind of hope they retcon that at some point.
In my head the justification for all of that is that the queen arose as a necessity to have a single individual for the crew of the Enterprise to interact with. This required her to have a certain amount of autonomy from the collective consciousness, the end result was that she turned into a bit of a dictator and because she had control over the collective she essentially took over without much fight. This would have been obvious to anyone else that this was a possibility, but the Borg had no experience of individuality in the collective before that, so the concern never occurred to them.
Eventually she died and the collective were released from her, and now they are back to being a hive mind. A hive mind that has learned not to do that again.
The reason seven of nine did not become like that was because the queen knew that that was a possibility, and so kept her largely connected so she could to a large extent control her.