Corporations are organizational models employed by humans in pursuit of human motivations. They are not entities unto themselves. Everything is humans, all the way down.
I'd also like a pony.
Conscience is fundamentally a trait that requires some kind of physical personhood - an actual self-identity with empathy attached to it. Corporations, being pure legal fiction, have neither.
This is why it is imperative to keep them as small and toothless as we possibly can as a society, even beyond issues with monopolies.
Sociopathy is all about driving the interests of the individual. Boards not being liable for the actions of companies allows those interests to always be aligned. Taking that away would require them to think about what's good for the business but also what's good for themselves and those things won't always align for all board members the way they do now.
The problem is that the more people you have working together on something, the less you can rely on informal human interactions to keep things running, and the more written rules and rigid processes you need. Those written rules and rigid processes increasingly take out human factors (such as empathy) out of the equation, and the result is that the entity as a whole behaves in an increasingly sociopathic manner even when its goals (as set by e.g. the board) are ostensibly beneficial.
And, for the same reason, they have no capacity for autonomous thought and action. Corporations are just organizational models for coordinating human activity, but all of the agency still originates with individuals, because there's nothing else that it could originate with.
All malicious acts you are attributing to corporations actually originate from the malicious intent of individuals who are merely using the corporation as an organizational model.
> This is why it is imperative to keep them as small and toothless as we possibly can as a society, even beyond issues with monopolies.
Keeping organized forms of social coordination "small and toothless" is inherently antagonistic to the concept of society itself -- the proper solution is to constrain malicious behavior without interfering with non-malicious behavior, regardless of how that behavior is coordinated or formalized.
There's also a paradox here, in that I have not seen any mechanism proposed for combating the implicit sociopath of one kind of organization that doesn't rely on creating even greater concentrations of monopoly power in the hands of an essentially equivalent form of organization.
Corporate personhood applies primarily to private law -- contract liability, civil torts, financial obligations and the like.