Problem with wearing pilot uniform is that anybody can buy the kit. Someone turning up in a pilot's shirt and trousers could be the best pilot in the World, or the worst - or even not a pilot at all. A person wearing pilot uniform while not actually on duty as a pilot always looks a bit suspect, I think.
Appearance at interviews needs to be smart and show that you respect the job, the company you are applying to, and the people interviewing you.
Would you turn up for work as a commercial airline pilot without a tie? It might be the norm where it is very hot, such as Australia, I don't know.