It's curious that the US doesn't use diacritical marks more often as we are a nation of immigrants and the original names would have included them.
What a luxury to have different languages with scripts that differ only in the tiny flagella like accents, cedillas, bars, and the occasional eszets. What good would it do to maintain them when a large number of immigrants don't get to keep their цs, жs, and ыs anyway? Or what about me try to explain the difference of aspirated and unaspirated retroflex and dental d to ears not attuned to such differences?
Seriously, though, is their any point in distinguishing between German u and ü without somehow marking the French u as French? And isn't accent a tiny issue when Jesus in the US does not usually have the English pronounciation, and it is difficult to know how to pronounce Angel in any given instance? Note that in these examples, as well as the introduction of u (of the recent Muriel thread variety) in the Norman period, we often do not extend the alphabet, instead given new values to old symbols in particular contexts. This often goes so far as to be virtually unidentifiable to people who are unfamiliar with the source: Tamil (or properly Tamizh) is most often transliterated using zh to stand for a retroflex kind of l instead of inventing an accent on l.