I think I've done it! I've solved the mystery of the opera Supertitle War!
The answer to the dichotomy between critics' despair and audience's support is quite simple: Most critics are seated downstairs, where one must actively look up to read the projected translation. This is distracting.
From the more affordable echelons of the balconies, however, the titles fall directly and neatly into the line of vision, unobtrusively providing a useful precis translation of the foreign text. Ironically, in this case the cheaper seats are better!
I won't try to insist the system is perfect; knowing the opera intimately beforehand is the ideal, but improbable, and in some cases impractical solution. There are many hitches that still need to be worked out: awkward paraphrases, laughable glitches and glaring double entendres are a problem from any seat in the house.
However, as a firm believer in opera in the original language, any device that helps audiences better understand that language, and thus appreciate the composer's marriage between music and text, is to be applauded.