We actually got quite a few responses from very influential people, not just Naval. The reality is, a lot of them spend hours on email a day. If you give them something worth responding to, they will respond!
Since I worked from a BlackBerry for so long, I find that emails that are about the length of these 3 messages (individually, not combined) is about as much as you can expect people to really read... more than that deserves a phone call most of the time.
The problem here is that not everybody is objective when it comes to determine what is worth responding to. So this will be applied as a winning recipe because it worked once for someone and that someone blogged about it.
I can see a whole pile of heavy hitters waking up to people trying this scheme out wondering what is the cause of this inbox deluge :)
In either case there's no harm in sending the email. Of course your conversion rate is going to be low. But if you can send 10 well written emails and get 1 valuable response, that certainly seems worth it to me!