Have you considered it's the way you criticise?To Thais? Of course - unfortunately they have been conditioned through cultural learning to view ALL criticism as something close to a personal attack.
I know a few farang consultants hired by Thai companies, and they get paid very well for their criticism. I know a lot of Thai people as well, they don't seem to have much of a problem with it either, as much as anyone else really.
This make me a rose tinted glass wearing thaiophile arguing against the 'truth tellers' though doesn't it?