I totally agree with @kmb385 in his answer: http://meta.stackexchange.com/a/164209/234982https://meta.stackexchange.com/a/164209/234982. I just want to go little further - keep reputation for edit as well. When I see ugly formatted question / answer, I clean it first so it is possible to understand it. And sometimes I receive small reputation for it. That is fair.
But it happens that user is deleted. Then all my work is lost. My work disappears. It is disgusting when somebody voids your work. And even my reputation is decreased. So this is the second penalization. I realized that I do not have any will to fix the questions from beginners or that were downvoted. Why shall I spend several minutes of my life doing some work that somebody can erase?
Please keep the reputation of deleted users please. There is no reason to punish the people that were helping them. That is unfair.