You're wrong about double-taxation. Most countries have an agreement with US to avoid double-taxation, so in practice you pay the larger of the two - US tax or the tax in the country of residence.
Another thing to note is that if you give up your citizenship you only pay taxes for all gains up to that point, so you actually have a choice - stick the American passport and pay US taxes, or give it up and don't pay US taxes.
I don't like the system either, but it's not THAT bad. Certainly did not deter me from coming here :) and will not deter me if I want to go somewhere else.
Another thing to note is that if you give up your citizenship you only pay taxes for all gains up to that point, so you actually have a choice - stick the American passport and pay US taxes, or give it up and don't pay US taxes.
I don't like the system either, but it's not THAT bad. Certainly did not deter me from coming here :) and will not deter me if I want to go somewhere else.