To raise from the public under the JOBS Act, you have to do your ICO through a regulated platform. As far as I know, none of those support blockchain projects, so it's not actually an option yet.
Plus you can't raise more than a million dollars or so that way. And there's a limit per person, so instead of just sending ETH, everybody would have to go through the platform's KYC, and declare how much income/assets they have.
In the meantime, people in countries with more economic freedom than the U.S. can just deploy a couple pages of code, make some basic efforts to block U.S. investors, and be done with it.
