This is quite true, however there is most certainly a Bangkok Professional class that is nothing like you describe. I have a Thai woman like this working for me who is of this class and the last thing she would ever be interested in is a western slob...hence she is married to a Thai her own age, even though she live in Oz. ...mind boggling isn't it I've also got colleagues in Bangkok of this class and I can tell you hooking up with a Westerner is not a badge of honour......
Now, I understand that most Aussies experience of Thai women is limited to girls from Isaan that they meet around Sukhumvit, Walking street and Bangla rd and this is a different story
there is some truth to what you say, however, especially in the poor areas, the girls there lose and gain face by the amount of money their sponsors or husbands are paying them, (much like keeping up with the jones')
once you start bringing in different classes (eg Hiso, middle class) even to the majority of them, marrying a farang is a step up, well for Hiso, the guy cant be a total loser, he has to be well presented, financially ok, not a fat balding drunk etc. etc.
thats why even the good girls, or the hard working office girls of upper management, will often go and ask foreigners to introduce them to any guy, its a combination of expectations, and gaining of face, amongst friends and relatives. Its usually only the parties involved that think "oh what a catch ive got", while the people around them either dont care or look down on them,
its actually quite an interesting phenomenon