Amuse-bouche

From a friend on today's twitter:

Charles Isherwood calls two Mamet plays at the Atlantic Theater Company an "amuse-bouche." Ok, we know you went to college and speak French.

It's so pretentious when journalists use words that almost none of their readers will understand, just to prove how smart they are.

Is it though? It's possible Mr. Isherwood tossed in "amuse-bouche" to intentionally mock his readers' ignorance. (Isn't that what we're afraid of?) But let's consider the same circumstance from the nerd's perspective, which is the only one I can offer with any confidence: YAY! A new word! Presented in context so as to provide immediate practical application! FREE LEARNING!

I say this only partly in jest, but also with some amazement and no intention of poking any eyes out. Because I would like to understand: why is a writer pretentious for using a word you're not familiar with? And more than that, why would you assume that a word you don't know the meaning of has no value for you, or that the writer who uses it has no cause to do so?