I wouldn't make them lockerable until Ying/Yang subdungeon is finalized. This subdungeon is still completely useless to everyone except assassins and maybe rogues. For anyone else, the amount of effort required to defeat Ying/Yang isn't worth the reward, and since the subdungeon offers no exploration and you need to be a high level to attempt it that makes the resource expenditure even more odious.
Pretty much all of the "no-explore" subdungeons need considerable revision since they're entirely useless under a wide range of scenarios.