Congress, the FCC, and the Clinton adminsistration are currently seeking ways to rope in the Internet message traffic and label it. Yet, here, you propose further regulation, not less. Enforcement would be a nightmare. Often, those who would attempt to comply might not include ALL the keywords required or might use the wrong keyword. As failure to comply became a problem, more regulations would be heaped upon this already rotting dung pile to force compliance.
EPIC follows the controversy and anti-spam legal actions closely.
You can also find a healthy debate on unsolicited email on FTC's privacy forum. There's one going on now. Everything you've mentioned above as solutions is being debated. People complain, send complaints to the spammer's ISP or postmaster, and the spammer gets shut down. Second, there are technological solutions to spammers.