That's why we draw a distinction between following the letter of the law and the spirit of the law. Or, as the dude put it, "you're not wrong Walter, you're just an asshole."
Let's not forget that US corporations are also obligated to maximize shareholder value. Reconciling these oftentimes conflicting edicts is hardly a trivial matter and this illustrates how black and white simplifications do not capture the underlying complexity of the issue.
Don't necessarily disagree with you about the usefulness (or lack thereof) of this idea. Check out http://en.wikipedia.org/wiki/Dodge_v._Ford_Motor_Company for an illustration. But, however you want to characterize the idea, it is still an unavoidable constraint on US corporations. I only bring it up to illustrate the doctrinal ambiguity that is seen in almost every part of the law.
I take your point. But what may seem ambiguous to a corporation is not at all ambiguous to most citizens – myself included – who tend to see such tax structures as an underhanded way to game the system.
To frame it in more pragmatic terms, deploying these tax structures may hurt a company more than it helps due to the opprobrium they attract. Of course it's difficult to quantify the effects of bad press. But not all decisions should boil down to a cost-benefit analysis – what's wrong is wrong.
Apple's tax structure rightly prompted outrage, and Ireland was shamed into closing the loophole: http://www.bbc.co.uk/news/business-24542794