I see not much more than pseudo arguments and evasive answers, i doubt there is much sense in this discussion other than stirring up moods...so guys - if you think slavery is a typical corsair thing, you now own a proud place in the council of elders and have a big influence on how the corsairs will develop. Gather the support of the other factions, then you will be able to get the corsair laws about slavery changed.
And if you are afraid the corsairs grew stale, then get creative and pray for a story dev that doesn't take joy in crippling and fooling you.
Other than that - play your sairs as evil and scary as it gets - just keep it within said lore boundaries until you actually do more then screaming around here...