Technology wasn't standing in the way in 1963...my guess would be money.
Four interesting things from the catalogue:
1 One section of the ex. was called Plaisirs and had the following intro, in part:
Brassai a voulu ici faire une étude de moeurs nocturnes...
Voluptés de Paris was supposed to be published with a text by Mac-Orlan, but the publisher hijacked the pictures in order to put out what this introducer calls "un ouvrage à tendence licencieuse" (9). Also, Polllack (Jackson??) said that VDP was Brassai's best book but Brassai didn't agree...
2 the couple at the monocle (i am guessing this is what it was) appears as "Couple de Femmes, 1932," with no accompanying information. # 24 in the catalogue, page 9.
3 there was one photo from magic city, no. 30, described as follows:
Le bal de Magic City, 1932.
Grand bal d'homosexuels autorisé. De nombreux hommes étaient habillés par de grands courturiers, et "parfois d'une beauté incroyable". (B.). Brassaï y prit une vingtaine de photos, avant de s'en voir interdire l'accès. (10)
4 a photograph of colette taken in 1954 with her hair in her face, apparently, was included in the exhibit, no. 91. According to this text, the two met in 1932 when Brassai was approached by her about the possibility of illustrating "un livre sur les invertis qu'elle préparait," which i assume to be Ces plasirs.
(He didn't, by the way...)