True, but people are already using email. Everyone knows how email works and how to attach files. Not everyone knows what a "writeboard" is and how it's different from a "message"
I agree fully that everyone knows how email works, and I'm not debating the point that email-capable devices outnumber javascript-web-capable devices. I'm questioning the point that because there are more email-capable devices, email is a superior medium for project communications -- because there are enough devices with modern web browsers to let people use more advanced tools.