Sure, and why not pull AdSense ads from gmail, too? Come to think of it, why not dump every site in the AdSense network that doesn't convert well for advertisers? If that happened, smart pricing wouldn't be necessary.
Ain't gonna happen, though. AdSense is a market-dominating, lowest-common-denominator, advertiser-take-potluck network. Google can't redefine it at this late date. On the other hand, Google can (and quite possibly will) introduce product extensions or subsets of the network to stay competitive and to attract a wider range of advertisers.