A1. (By @Veremund ) No, because black suits are for nighttime. That's why tuxedos / dinner jackets are called "evening attire" and are normally black (or a color so dark that it appears black).
A2. (By @unbelragazzo ) To me the silk facings give the tuxedo a richness that the black suit on its own doesn't have. Without the facings, a little bit of color helps to enliven the suit. Navy and charcoal are also more forgiving for a wider variety of complexions. Then there's the funereal connotation of the black suit. But I wouldn't say a black suit is terrible, just obviously not as nice as a tuxedo while kind of trying to be like one.
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