wanttoflyagain
I wouldn't feel too bad. As has been suggested perhaps you are too experienced for them and they fear you will not easily settle into their LLC conditions. It's just as easy to be eliminated for being "too good" as for being below standards. Try an airline with higher standards and you may get further.
I learned this lesson with hospitality. I couldn't get a job until I stopped dressing nicely and instead turned up for job interviews in jeans and a casual shirt with my hair down. No I didn't go like this to my assessment day btw. But it does prove a point. Maybe you just didn't look budget enough for them...?