I see Thai males on a daily basis without a shirt on. If the locals do it, what is the problem with Farangs? There used to be the argument that Thai males had the body to go topless, where as many Farangs were flabby. However, these days I see many Thais walking around with their 7-11 stomachs that even make me feel slim

Farang females are usually quite discreet about baring their boobs, and I must say, I've never seen a Thai female under the age of 80 walking around topless (certainly not outside of bar areas where a little free advertising might be order of the day), so yes, there should be an element of discretion. However, if the practice is banned altogether it will be yet another nail in the tourism coffin, as those ladies who like to go topless will simply go elsewhere.
I honestly don't see the problem, and as for 'the rules', what rules? It's only a fairly recent innovation that Thai females started hiding their boobs anyway.