http://www.bendlawoffice.com/2011/08/01/reasons-to-incorpora...
The reason to register in Delaware is because of business friendly courts there. I don't believe there is a tax advantage
Delaware has a corporate tax rate of 8.7%, California has 8.84.
So yes no one is incorporating in Delaware becuase of taxes, WA, TX, NV and a few others have zero corporate tax.
Not sure how state tax rates interact with the federal one though
But most importantly to the (joke) argument that we're the last communist country there's a massive popular adhesion to the points listed above and for some reason a deep seated mistrust of the wealthy.
As for the communist thing, ah I didn't realize it was a joke argument, thought it was a serious one
Corporations, such as Microsoft, which are headquartered in states with nicer bodies of corporate law frequently choose to incorporate in their home state, such as Washington.