If they aren't pronounced, why did you put them there?

Because non-rhotic varieties of English use them to distinguish /æ/ from /ɑ/ (i.e., a from ar). Cf. the strange, to USan eyes, reference in the first chapter of Winnie the Pooh contrasting ther Pooh with the Pooh (i.e., /ðə/ and /ðiː/). (It's one of the reasons to use IPA rather than ad hoc pseudo-phonemic spellings.)

Ceci n'est pas un seing.