On the other hand, a wailing famished baby's far more of an aural nuisance than happily suckling one.

True, but that points up another interesting issue to me. Taking one's baby somewhere more private to feed it inconveniences the mother; you'd have had to leave your con socialising or your interesting panel or whatever, for example. I do find myself wondering to what extent the "boob nazi" movement is powered simply by the fact that overtired mothers don't want to have to make the effort to maintain boundaries; it's easier for them to run the risk of squicking other people.

I'm not by any means one of these infuriatingly self-centred childfree types, but I do think that often parents lose sight of exactly what a vast gulf exists between the worldview of a parent and that of a non-parent, and begin to expect that everyone will feel the same way they do about issues like this one.