This is true, but eliminating corporate taxes has some other nice secondary effects. Streamlining the tax code invariably means streamlining the IRS, whether by design or not. It frees up a huge amount of essentially wasted billions in tax prepration, lobbying, lawyers fees, accountants fees, and makes irrelevant huge tracts of frozen bureaucratic tundra.
Corruption, as you correctly point out, will always find a way. It's just nice that we'll get a lot of fringe benefits from making corruption relocate.
Also, once streamlined for corporations, it will make it a lot easier to go all the way and streamline the tax cade for everybody.