Corporate personhood exists so that you can be hired by a company instead of a specific person in HR or have a cellphone contract with Verizon instead of a particular sales associate and companies can buy real estate and so on without requiring a whole bunch of extra legal work defining all the ways in which corporations are legally treated like natural persons. That necessarily includes giving corporations some of the same rights and duties as natural persons. But I do think that corporations have been given too many rights which have been interpreted too broadly. The notion that a corporation has a constitutional right to spend however much money it wants to influence politics due to free speech is ridiculous.