netmeg - 6:41 pm on Jun 16, 2010 (gmt 0)
My brand new BlackBerry Bold 9650 which I received less than two weeks ago does not display AdSense with the native browser.
Opera would display it, but then you're relying on someone to go to the trouble of downloading and installing Opera.
And there are tons of phones that *aren't* iPhones.
Carriers are phasing out "all you can eat" data plans, which means stripped down sites optimized for mobile may consume less bandwidth.
If you're in a competitive environment and none of your competition offers mobile pages while you do, you may have an advantage.
Those are a few reasons; I'll probably think of more.