@roger,
I can deduct something around $90,000 (didn't do my taxes this year, so I don't recall exact amount) but it's a lot more than just taxes. It's a fundamental notion of America believing they have the legal right to control their citizens regardless of where they live and America's penchant for prohibition (e.g. online poker).
Few countries are that authoritarian, and some are very very generous when it comes to taxes. Given that I don't use American infrastructure, American citizenship is both a financial liability and an impediment to freedom to me.
Also, given that many nations have visa restrictions that reciprocate how their citizens are treated it also can make for travel restrictions. For example, American citizens have to apply for a visa in advance to go to Brazil while a Costa Rican could just show up and get one while they are having their passport stamped. This is because that is how Costa Rica treat's Brazilian citizens entering the country but the United States makes it very difficult for Brazilians to enter the country. It doesn't make financial sense, mind you, for Brazil to reciprocate this way (Costa Rica doesn't with the US and Americans can enter without pre-obtaining a visa) but it's another American citizenship tax when operating abroad.