11% would be a decent tax, especially on a guy making millions. Romney's, like mine, was actually closer to 14%; which means about $7,000 for me, millions and millions for him. What's your moral justification for making either one of us pay a higher percentage than the other? Don't envy his stuff, man. Don't vote based on envy, which is simply self-justified greed.
You are focused too much on the absolute value of the dollars. The moral justification is that beyond a certain number those millions of dollars have less value than your $50,000. In other words basic necessities take up a far larger percentage of your income than Romney's. The additional tax revenue from people like Romney helps pay for the social costs of company's like his that force other companies to pay their workers substandard wages and benefits and thus turn to the government for help in order to increase profit margins to give people like Romney even more money. Do you see how this cycle works? If companies paid their employees a more reasonable wage, a so-called living wage, I could see the case for lowering taxes.
As for the rest of your post, competing on taxes is a downward spiral that leaves governments unable to take care of their people in order to export wealth out of the country. A certain amount of tax competition help keep things lean but it's better to compete on things like education and infrastructure that hard to replicate. The reason tax competition is so popular is that it just takes some paper shuffling rather than real investments in a country's future.