And as awesome as Alice Krige was at the role, her existence completely ruined what made the Borg unique and scary.
They were a collective without individuals. Having a leader just made them another generic villain of the week. And boy did Voyager and Picard run with that.
Maybe it's a commentary on how any system of domination is going to coalesce into a centralised hierarchy of domination which will always be more fragile than a non-coercive system.
Or maybe it was lazy TV writers who needed to put a face on the threat so audiences "got" it.