Exchanges serve this purpose, as well as the benefit of having your currency quickly trade and liquidate-able. Decentralized exchanges (such as Bitshares) are the most secure.
But I agree, whoever puts all the work into handing all those different types of Cryptos into a single wallet would lead the industry. I think the amount of labor is cost prohibitive.
Exchanges are a great means to trade from one crypto to another. But even in my short time, I know that exchanges are NOT a good place to store your cryptos. Too prone to failing, one way or another. But yes, I agree, first wins similar to BTC :)
Whats your risk on the decentralized exchange stem from? vs a wallet?
With a wallet, YOU own the keys and have full control. On an exchange, lots of things can happen. Mt. Gox is the most prevalent example...
https://www.google.com/amp/s/www.wired.com/2014/03/bitcoin-exchange/amp
Wasn't decentralized. Your currencies are in your hands (just like a LOCAL wallet) like on Bitshares. Unless I am somehow mistaken.