Ethereum still involves transactional costs. One way or another you have to pay for decentralized security. But the costs should be far less than legacy systems.

Also because of network effects, it is probable that only one cryptocurrency will dominate, likely Bitcoin. So it is convenient for ownership to take place on Bitcoin and not in a competing altcoin. We'll see how things progress when Ethereum comes out.

hahah, ethereum.

Or you know, you could use practically any other system that doesn't try to be money (or en ethereum's case, an everything wannabe)