I have now heard from the entirety of the U.S. expat population, in its millions-strong ranks, about the role of FATCA and FBAR in their lives -- along with dissenting views from a few locally based Americans. Here's an introductory sample of the range of arguments, after two crucial stage-setting explanations.
Something most "normal" Americans don't realize: U.S. tax policy, unlike that of most other countries, works on the principle of "citizenship taxation." If you're an American citizen, then wherever you live, however long you live there, however you earn your money, and wherever you spend it, you're still subject to US income tax law. No matter if you're living in Moscow or Manila, as long as you hold US citizenship you're supposed to send in your Schedule 1040 to the IRS, just as if you were living in Dubuque. This is so even though you're already paying taxes on that same income to the government wherever you happen to be.
There are escape clauses and caveats. If you're physically out of the US long enough (at least 330 complete days per calendar year), then you can exempt some or all of your income from taxes (now an exemption of as much as $92,900 per earner). Also, some or all of the tax you pay to a foreign government can be credited against the US tax you owe. It's very complicated, and I'll leave further nuances to the CPAs. The main point is, America's policy is unusual. No other major countries (that I'm aware of) apply the principle of "citizenship taxation"; they operate instead under "residence taxation" rules. If you're an overseas German, Canadian, Filipino, etc, you pay income taxes where you're making your living, not back to the motherland.