hmmmmmm I have wondered about a public posting key account before... my theory is if it is given to steem people the ones that can afford new accounts will pass and the ones that can't will attempt to use it for their own benefit through voting/resteem. So I think maybe a useful way to do it would be as a promotional tool for steem, like a trial-run somehow given to people outside of steem that still have to go through the long account creation process (my friend had to wait almost a month after signing up until he could actually start posting/voting/etc.) if someone in that scenario had a public account key they could at least interact and comment on things they're reading, but I'm not sure how a public key could be distributed in such a way that mostly outsiders have access to it.
Anyway, I think having a link to the website right after explaining how you're some epic hacker is a little intimidating, lol