I'd say there is a potential argument to be made for the endless supply of altcoins being mined. With established currency's such as Litecoins and Bitcoins dominating the marketplace and being the fore-runners in cryptocurrency innovation, it does seem kind of pointless for the random currencys like BossCoin to exist. However, mining makes perfect sense for the mainstream currency's, as it is what insures the blockchain moves forward and new coins are created. Its essential.
Trouble is the more alt-currencies we have, the more "pointless" mining we have, and we do live in a resource-starved world. Of course its a free market, so people can create as many currencies as they want ......... just gets completely pointless after a while, crazy even, especially if the currency has nothing new to offer the world.