Much worse than using high-falutin' vocabulary (I might sometimes take advantage of 'utilise' myself) is using high-falutin' grammatical constructions AND USING THEM WRONGLY. Which takes us back nicely to the OP:

> "Having lived in the U.K., I know many whose first (and only) language is English and who make routine errors when speaking and many more when writing," says Madani.

The latest horror is people trying to use the 'so [adjective] a [noun]' construction but instead saying 'so [adjective] of a [noun]'. Folks, when you say 'so [adjective] of a [noun]' you don't sound no ways educated. There's a reason that Abraham Lincoln wrote of "the solemn pride that must be yours to have laid so costly a sacrifice on the altar of freedom" and not "so costly of a sacrifice"; and the reason is that Abraham Lincoln was not bloody illiterate. (It may actually have been written by John Hay https://en.wikipedia.org/wiki/Bixby_letter, but Lincoln's secretaries weren't illiterate, either.) Now you might not think it makes much of a difference; but 'much' is a determiner, not an adjective, which should be clear if you think about it for a much time.