I don't really disagree about the shift in power, but it doesn't have anything inherently to do with the structure of corporations (liability shield, "person",

I don't really disagree about the shift in power, but it doesn't have anything inherently to do with the structure of corporations (liability shield, "person", tax status). If you want to disallow corporations from political donations, then you are blocking 1000's of small businesses from having a voice while allowing billionaires like David Koch and George Soros have unfettered access to politicians. Whatever your particular concern is rooted in, there is probably a general solution (e.g., public financing of campaigns) other than singling out corporations which are a useful and diverse group of entities.