As of now, there's no easy and simple way to write messages on the Ethereum blockchain. MyEtherWallet doesn't count because it's not really something that tech-savvy non-coders can figure out.
Put in a low fee to recoup costs for hosting/domain and also to deter spamming the network. It's easy to circumvent if you know what you're doing though, so it's more of an honour-system thing.