RTA,
I really don't think JetSTAR pax are going to be worrying about:
".... head-truning grace, poise, or WOW factor."
These are people that would normally catch the bus, if flights weren't so cheap now days. They would rather have someone they can relate to, NOT a GLAMOUR FA.
As for the 'T-shirts', remember this is a BUDGET airline.
Welcome to the 21ST century.