I'm not sure I understand the question. It's up to each publisher to decide if they make enough on AdSense to justify putting its ads on their site. The success of Google's ad business suggests that even net of fees, many people still think it's worth it.

Now, personally, I don't think Google pays me enough to run AdSense on any of my sites. It's frankly not even close, so the fee isn't the issue -- it's just a bad fit for the volume and type of content I produce. I can see why it's great for many other publishers though.