As an American citizen, I'm still subject to federal income tax, even on income earned while I'm residing outside the country, for work done entirely outside the country, for a non-American employer. That being the case, I see no reason why similar rules shouldn't apply to American corporations. If we say an individual still derives services and value from their citizenship even when outside the country, and thus needs to pay in to support that, why not also American businesses?
I don't know enough about business structures and tax code to say _how_ to make it happen, but from a sense of fairness, I think that roughly equitable rules for business and individual entities is a good thing.