You don't have to have an M rating for it to be a good game, if you want a game like you are describing then go play some other fps that fits your needs like battlefield or CoD but swearing is not necessary for a game like this. Let BUNGIE decide the fate of this game's rating because they have a better idea of what would make it better.
English
-
His point is that swearing would be undoubtably found in the conditions under which Destiny takes place. To make the story more immersive, swearing would be rather necessary.