It is also indeterminate in how regressive it is[1]...some companies and industries can offload almost all of the tax burden (incidence) onto their workers, while others offload it onto their shareholders. Even in the case where shareholders shoulder the majority of the burden, ownership distribution can still heavily affect how progressive it is in reality.
The worst part is that it just isn't that great of a form of revenue. Doubling our effective corporate tax rate would be impossible politically. Superficially, rates can be raised, but tax lawyers will exploit the shit out of it anyway. A coalition might be able to raise it by an effective 25% max before every corporation in the US teams up to vote them six feet under. Seems like a lot of political capital to waste just to get a measly $80B/year. [2].
IMO, the perfect solution would be to eliminate the corporate tax altogether, and tax capital gains and dividends as income instead. At least then you can be assured that it is progressive, and you have more direct control over how progressive it is.
[1] http://www.urban.org/uploadedpdf/1001349_corporate_tax_incid... [1] http://www.kc.frb.org/Publicat/RegionalRWP/RRWP07-01.pdf [2] http://www.taxpolicycenter.org/taxfacts/displayafact.cfm?Doc...