dsims: Thanks for the feedback, but without any specific explanation of the problem I can't do much with it.
Currently AdSense Manager may be uneccessary for many people but it does simplify placing the Ad Code into blog sidebar, posts and themes. I think you would have a hard time finding a plugin which is useful for every single user.
More than half the code is no longer related to AdSense specifically, allowing in-WordPress modification of multiple different Ad networks: which suggests you didn't read the code.
The AdSense related stuff is in 2 parts: support for old-style locally configurable blocks (which some still prefer) remaining from previous versions, and secondly for Managed Ads arranged through Google. For the second, the configuration options are limited by design: although the Google system does not allow you to automatically wrap Ads in specific tags, nor select which pages of the blog they appear on.
Finally, because of the limitations imposed by "Managed Ad" networks, v3 is a move towards doing better what is best done locally. That is ad switching, user-dependent ads (i.e. different ads for members, depending on referrers, depending on post topic, category, etc.) which is not possible through any online network.
That, ultimately, is the source of the "obsolete code": If you don't like it, or want it, don't use it.
Any feedback is welcome, as long as it leads somewhere.
Thanks.