The Queen always made sense to me. When you throw in things like "hive mind" and the nature of the Borg in general it seems natural that they would have a Queen.
In hive mind insects the queen does not rule or direct the hive. The Queen's role is producing more insects.
The Borg were already having conversations with the Federation through Locutus and Hugh, so the introduction of the Queen certainly didn't add anything unique on that front.
Right. She didn't add anything. She filled the same role we already saw with Locutus. Therefore, from an In-universe point of view if they already had the Queen, they did not need Locutus. This makes the whole point of Best of Both Worlds pointless.