There are so many coins, but many of them just a copy of anothers. Why they waste their time for nothing? 
Its not a waste of time, you did not really know the essence of business, developers are creating coins to get profit and because of that, ico's are being made to be promoted and earn investors. In this way those developers will have profit from their created coin and grow its value in the market at the time goes by.
You're correct, creating on their own coin makes them to be known and to be competitive enough. Also, regarding from copying to other ICO, well that's the game of business which you need to caught the attention of every client from others which you must have specialty like by having unique features or platforms the ICO project you have.