The idea of corporate personhood is to make it easier for big money to suppress the people.
It's not about letting corporations have a voice - Because they already had a voice, it's called their CEO. It's about making it easier for corporations to use their larger reserves of money to outbuy, outspend, and essentially suppress the people so that they, the corporations, can make even more money... Sometimes at the cost of the average American.
Edit - What were the founding fathers words? Oh yes, 'We The People', not 'We the Corporations'.
Our country is about the collective ideals of the people, not the ideals of a collective.