There are some benefits to appearing as Li Qingyue; there's no need to put on airs anymore, no need to awkwardly hide one's true capabilities, no need for feints and everchanging maneuvers, no need to cautiously modulate one's techniques to reveal and conceal, when it's time to cut down an enemy, one can straightforwardly display Mo Zhu Mountain's fundamental sword qi and Qiankun Flying Dragon Sword, the moves one is most skilled in.
But there are also drawbacks to using this identity, such as not being able to slay people openly as before. When you walk the path of righteousness, you must make sense, abide by rules, and uphold the sect's reputation. Even if planning in secret, ambushing and robbing, wiping out entire families must be justifiable.