We are aware that having it on by default means that we might not be the first choice for some people anymore when it comes to adblocking (usually those who are aware of the fact that they can turn it off but - don't ask me why - rather than that install a different extension). We updated the text on our Acceptable Ads page
to better describe why it has to be enabled by default. On there you can read
No applicant will be favored or treated differently, and no one can buy their way onto the whitelist. Everyone has to comply with the criteria and everyone has to go through the same process before the ads qualify as "acceptable."
If you disagree, what would you propose instead of having Acceptable Ads? We're always trying to find solutions for providing the best user experience while growing our userbase without harming the free and open nature of the web.