Well this is how a hasty decision ends up. As long as there are earmarked coaches in sleeper which are de-reserved, i dont think railways and passengers should have a problem eg Allp DHN, Sabari exp, MAQ-Egmore and few others.
The issue will be there for those trains where there are no earmarked coaches and sl tickets are issued eg Mangala, Nethravathi. Lots of passengers travel in these trains during the day time and do create inconvenience for reserved passengers.