Sometimes we have 2 stets armor or more weapons for change and we want be sure that we will not sell them by mistake to npc. So locking items should prevent selling by mistake - on npc list to sell items lock item, unlock item. And when we sell some trash to npc we could have option that we dont see on list to sell locked items.
And when locking-unlocking items will be sorted you could add sell all items button.
Only this 2 things is missing in STO(for me) and i thing it makes more youser frendly