Nothing wrong with a small pleasantry here and there, be it g'day, so long, cheerio or whatever - it reminds us there are humans behind the mikes, and not machines.
Main thing is to engage brain before opening mouth, and to listen before blasting off on a frequency you've just changed to.
Incidently why has QFA apparently adopted the practice of saying (for example) "QANTAS seventysix twenty four" instead of "QANTAS seven six two four"?