You should care because decentralized cryptocurrencies like Bitcoin and Ethereum are–or at least could be–essentially an Internet for money, securities, and other contractual transactions. Like the Internet, they are permissionless networks that anyone can join and use. Ethereum optimists might analogize Bitcoin as the FTP of this transactional Internet, with Ethereum as its World Wide Web.
I’ve waxed about why I think Bitcoin matters. I’m a little less enthusiastic about Ethereum … so far. To be clear: as I’ve written before, Ethereum is really cool, truly innovative, and potentially revolutionary. However, it is now–probably–at the peak of its initial hype cycle.
DAO made the front page of the Sunday Times, so I guess it's a bit beyond cool kids and already to "stuff your dad has heard of".