1) Some banks to want to deal with the liabilities of American clients (even dual citizens). There have been many cases were they simply said that all Americans must withdraw all of their money in a month and that they are no longer welcome to open an account [1]
2) I must report ALL of my money located abroad (since I am worth more than $10,000). That includes; bank account, pension fund, joint bank accounts (even with a non-American spouse), tax account after working at least once as a contractor, etc. No free tax software deals with all of that, so I must pay an American tax accountant located in my country a yearly I-am-an-American fee. If there is any mistake I could be fined up to half of everything that I own in America and in my country. [2]
3) Since I am lucky enough to have another citizenship, if I want to get rid of my American one, I will have to pay several thousand dollars to do that. [3] And there have been several cases were it has been more difficult for those people to receive visas to visit America.
[1] http://www.forbes.com/sites/deborahljacobs/2012/07/31/most-f...
[2] http://www.forbes.com/sites/robertwood/2012/06/04/fbar-penal...
[3] http://nomadcapitalist.com/2015/11/16/renounce-fee-relinquis...