The Internet is a free place and people can do as they please - including block whatever ads they want. And I say this as someone who makes his living in part from adsense revenue.

There is no better way to piss off a user and never to see them again, to do such a thing. There are many other ways to monetize a website that doesn't include adsense or other known advertising units that are blocked by such software. I would much rather the person blocking my ads come back, bookmark the website, tell others about it, leave comments (free content for me) etc etc etc.