All those shitcoins' stated purpose is just to build on top of an already pointless foundation. "Our coin helps you do this and that with other coins." There is no real use case. They don't solve any real world problem. BTC is a currency that provides privacy, transactions can't be blocked like your bank/paypal could, and its value won't be eroded over time because of inflation. If people started using it for daily transactions, all the benefits listed above would be realized. However it doesnt look like that's going to happen, so banks/exchanges will always be necessary, so it is fairly useless really besides gambling transactions.
The other currencies don't have any of that potential.