We should promote fair play in bitcoin and show the world that it's not every man for himself and not all of us are here to take each other's money.
Tx fee attached to a transaction is for the miner who adds the transaction to a block, it is the miners money. If you decide to or mistakenly send more than you should, it is still the miners money and that's the fee you agreed to pay for your tx to be mined. If one overpays in tx fees and the miner refuses to refund the excess amount, it isn't stealing or taking someone else's money.
Agreed, if the miners which mined such block are generous enough to return the money then the person that made such a mistake should be glad this was the case and consider themselves lucky this could be solved so easily, however we must not forget that things are never that simple, miners pay taxes and such a huge incoming sum of money could cause them problems and increase the taxes they will have to pay and have nothing to show for it if they returned it.