To get the closing price in a listed stock is MOC is for. You would want to use it if you have access to imbalances. An example would be if there is a buy imbalance in a stock that you own already then you may want to sell it to get the closing print. The imbalance may make a spike or the price may be different than the current price that the stock is trading at vs the closing price.
While this is a valid strategy it is also somewhat overused...everybody sees the same imbalances. The big problem is its still a market order and the specialist can have his way with you just like bubba the prison trustee. Edit = NYSE only