Hi Ace,
The numbers of C. parsonii that were exported prior to their ban are indeed very high and you are correct to say that most of those failed to survive long term, let alone breed successfully. This species has been breed on multiple occasions in captivity, however, and last I heard, F2 had been reached.
CITES issued a recommendation to ban importation of all but 4 Chamaeleo sp. (now Furcifer and Calumma sp.) because the Malagasy Management Authority failed to provide a satisfactory response to five recommendations the CITES Secretariat directed at them. Included in these are showing ability to form an effective regulatory agency and process and show scientific justification that trade would not impact wild populations.
A number of publications have considered C. parsonii locally abundant within their range. Based on the population density of C. p. cristifer, Brady & Griffiths (1999) estimated the population of C. parsonii be be in the 3.8-37.5 million range. While updated and specific population estimates are needed for most species, their ban from export was not based on data indicating their populations were declining, but rather as a means to prevent it from happening before an assessment could be made.
FYI, please call me Chris, I've only received my PhD Candidacy (not a Dr. yet) and the formality of being referred to as Dr. isn't something I am overly worried about once I do defend.
Chris