Over at his blog, Philosophy Professor Chris MacDonald argues that legal personhood for corporations is "absolutely fundamental to modern commerce. To believe otherwise, you basically have to be an anarchic anti-capitalist; indeed, you have to be against the very notion of large-scale cooperation and division of labour. But you're not, are you?
At heart, legal personhood just means that a corporation can be taken seriously by courts: it can be treated as a thing, separate from the human persons that make up the corporation at any particular time. This point does not imply any particular list of rights: the items on that list, and the limits thereon, are still very much up for debate. But what cannot be denied is that corporations must be treated as legal persons. The recent deliberations of the U.S. Supreme Court is something of a red herring in this regard. As is the American legal trend, in the decades after the Civil War, to apply the Fourteenth Amendment to corporations. Those are particular good-or-bad decisions; they tell us little if anything about the wisdom of granting some form of personhood to corporations. That idea, by the way, is a very old one, stretching back far before the 19th century. Corporate personhood is not an American invention or a conspiracy. It's a feature of every modern economy."
(For a lively and informative history of the corporation, and other sorts of companies, see The Company: A Short History of a Revolutionary Idea.)
Read Chris' full discussion of this here.