Why I Never Ever Fly Jetstar

Son visited us in southern Japan during the Obon Festival and despite my advice flew Jetstar. Well anyone familiar with airlines especially within Japan realize the absolutely shameful rorting conducted by airlines during these periods which add hundreds of dollars to tickets purchased other than at less popular times, and Jetstar would be by far the worst when factoring in their seemingly total lack of empathy and service.
My son travelled light from Tokyo but due to my wife and I buying him gifts to take back he was slugged 4000 yen ($65) for the 2.9kg over his 7 kg carry-on allowance. Ok we all know it's a budget airline but it's absolutely disgusting that at peak periods during the holiday season where Jetstar routinely holds passengers over a barrel farewise, that a little kindness and flexibility is not shown. And ohh how the staff seem to relish their role in all of this!
Do they go out of their way to ruin a person's hoilday? It would seem so!
Other reasons I would not fly with this airline unless absolutely desperate are:
dated and unclean planes, abysmal service, arrogant ground staff and an airline colour scheme that screams cheap and nasty!
Well what would one expect from a company owned to two other ratbag entities?

Domestic
Japan-Tokyo (Narita International)
Japan-Tokyo (Narita International)