Pronouncing the 't' still is considered lower class by many self-proclaimed language snobs. One basis of the snobbery may be literacy: those who are able to read are the only ones who would include a 't' sound. Of course, that bit of snobbery doesn't account for a word like fasten where no one pronounces the 't'. Which is to say, as with most bits of language snobbery, insisting that others pronounce a word according to your personal preference is most likely good evidence that the insisting person is an asshole.