I guess we will have to agree to disagree. Here is a good article on the web app vs downloadable: http://www.kalzumeus.com/2009/09/05/desktop-aps-versus-web-a...

I don't have an stats but from watching regular people use computers I absolutely believe that people are much more willing to give something a go if it involves clicking a button on a web page rather then downloads and installers etc.