France was not so interested in building CV's though it felt it needed more capable fast capital ships to counter the threat of both Italian and German new construction, as well as feeling the need to replace the very weak existing capital ships, which did not compare well with the existing competition to start with, not even suggesting the new constructions elsewhere. (Courbet Class was already obsolete when build, as was basically the Bretagne class, both being not very well protected and with no possibilities to get modernized to the same degree other foreign navies modernized their older ships, like the Queen Elizabeth, Cavour, Andrea Doria, Kongo, etc.) Besides that, their only CV was a converted Battleship hull, which was only useful to show how not to convert a capital ship into a CV. Bearn as a CV was a disappointment with a small air complement only and a very slow speed and range, even worse than the HMS Eagle.
So France badly needed to modernize the capital ship part of the Marine National, choosing to do the big gun part first, as these were missed most. The value of the CV was not fully understood at the time so the choice was logical to replace the old and obsolete pre-war (pre 1914 design) Dreadnoughts with more capable ships first. The role of the CV was still supposed to be that of a supporting vessel for the big gun ships to start with. In this view the large seaplane carrier Commandante Teste was build for this purpose as well.
The start with Dunkerque and her half sister somewhat later, was primarily a response not to Italy, but to Germany starting the construction of the Deutschland class in the early 30's, with the later Richelieu class build in response mainly to counter the Italian Littorio class. Both were seen as badly needed to compensate for the obsolecense of the Courbet and Bretagne classes, leaving France no other option than to follow the rest of the world in the big gun ship armamentsrace. Buiding CV's instead would be seen as a giant gamble with no clear view what this would bring. Note the proposed CV's of the Joffre class in the 1939 program were not the most clever CV designs still, though including some novelties of interest, but still not the volume of airpower needed for modern CV operations, like the IJN, USN and even the Royal Navy started to develop around this time.