When I became a Dominican in '57, the novitiate building built at the start of the 1900's to accommodate the normal number of entrants and novices was too small since in prior years the numbers of women entering was significantly smaller. The Community built an additional new building in the mid '60's, which, with the change in trend now houses retired Sisters. 
The call to community living then and now has changed and those of us who changed our vocations did not do so because of a change in dress.
The CARA data does not support your assumption. Women do not choose a lifestyle purely for the dress code. To assume that to be so, is rather insulting.
Women religious, detectives, nurses, college professors, doctors and lawyers aren't who they are, or better able to be successful,  based on their dress. We as their associates love and respect them for their skills....as it should be.