The Borg Queen works just fine. She IS the collective, she's just the higher functions of the hive mind. Remember, the Borg are not a natural hive, they're artificial so each layer has to be created, the basic hive runs on it's primary objectives, find new stuff, assimilate what's useffull and destroy threats. When greater thinking is required you have the Queen, who is unlikely to be a unique entity, she dies often enough that either any drone can be upgraded to fill th roll or there's just a group of them.
Think about it, why else would they have turned Picard into Locutus unless there was already a niche for him to occupy? The Queen just fills that role in other important areas.