I'll be quite honest. It's very difficult to draw the line between legitimate businesses and illegitimate businesses, and it's very difficult to craft legislation that deals with that. Now, having said that, I think the provisions that allow people to send electronic messages if there's an existing business relationship are one way of addressing that.
I think the other point worth emphasizing is that if you're like me, you're fairly careful about to whom you give your e-mail address. By doing that, I think in many cases you're going to ask why they're asking for it, and you're going to have a pretty good idea of what the person is doing. It wouldn't be that hard to build consent into that process upfront.