Why shouldn't a special prosecutor be appointed? Is not Hilary under investigation for criminal activity? He foundation pay-to-play activities for instance -- highly illegal.
What actual evidence is there of this? The clintons receive more than enough money through paid speeches and those would be the route you would use if you wanted to set up a quid pro quo. Using a charitable foundation to do this doesn't make sense generally nor in this case. Of course, lobbying and getting on paid boards after a government career is basically a quid pro quo( the presumption is that after you work for the industry you get a cushy career paid by the industry you helped) but that has been totally ignored this election cycle.
Not sure how soliciting charitable donations is pay to play. On the face of it laundering donations through a charitable foundation is pretty stupid and pointless and it seems unclear how donations would drive her to take the risk of doing a quid pro quo when the quid has little personal benefit to her.