I took corporate law in law school. Yes, in most instances executives are protected from suit, and from many forms of criminal liability unless their actions were CLEARLY not taken in the interest of the stockholders (a very high burden to meet). There are some instances where "principals" face liability, but even in these cases, the corporations usually indemnify the individuals either through private insurance or some other form of contract.
I had the advantage of being taught this class by a 'law and econ' guy who analyzes everything in terms of policy. Believe it or not, there IS a benefit to allowing limited liability (people take risks with their money that they wouldnt otherwise take, and society does benefit). The problem is that there isnt any mechanism by which society can be compensated for the externalities that the corporations impose on society at large.
One way to do this would be to remove the limited liability protection and force a system or reinsurance on corporations (think lloyds of london in the age of mercantilism), this would allow the market to assign a premium to risks, and force the investors to pay the costs of those risks, and relieve the random person that gets screwed through negligence, fraud, or malfeasance in excess of the paper value of the corporation.
As I said earlier, the even bigger problem is extending the "legal person" fiction necessary to sue a corporation into "natural person" rights and civil liberties. Imagine how powerful a person could be if he could live forever.... Thats what a corporation is when granted natural rights. An unkillable blood sucking zombie.