Why does the act of Hamlet jumping into the grave evoke pity ? and why does it not ?
In my mind, I tend to think that it does evoke pity. Particularly because it is one of the first times that Hamlet shows his emotion publicly and it happens that he is expressing terrible grief for this girl he loved who was destroyed by the intrigue and the absurd maneuvers of Polonius and Claudius and the court.
I think the argument could be made that it does not evoke pity given that Hamlet has been so constantly back and forth and it is difficult to trust his emotion, even when it appears to be genuine and powerful enough to bring him to act in public rather than rant in private.