I don't think your first point is valid. When Twitter was created, many people didn't understand what purpose it served compared to, say, a blog post or Faceboo

I don't think your first point is valid. When Twitter was created, many people didn't understand what purpose it served compared to, say, a blog post or Facebook status update. However, when you're operating in untested waters like this, you need to create some sort of platform that allows people to play around with what you have. The moment I saw it, I thought, "oh, wouldn't it be cool if I could see a map that showed a coloration of people's moods in a geographical context?"