The opt out rate is below 5% right now - that's what the opt in rate would be, probably even a bit less. There's no way to get any site interested in improving their ads like this. It's definitely controversial, I wasn't a fan of this at first either, but it really wouldn't change anything the other way around.

Also, we're clearly communicating this on our website, the first run page and in the settings UI and make it dead-simple to opt out. We're even planning to show a little notice next to whitelisted ads in the future.