Jeremy,
Perhaps this is a partially generational concern.
In the MWSD community today, there is much role swapping among dancers. Most often ladies are dancing the gents' role. The terms boys and girls, are roles much like ladies and gents in the contra scene. Although I call fewer MWSD events these days, in 25 years have never encountered opposition, or even concern about these terms at a MWSD event. Many out dated gender specific terms are used in the activity as well, for example, lads and lassies, and ruffles and beaus. All these terms are part of their dance "tradition".
The MWSD community is generally much older, and does not have problems with these traditional dance terms. As noted the terms are often selected to fit within the rhythm and rhyme of patter. As a caller who calls to both MWSD and contra communities, I am trying very hard to eliminate boys and girls, and it is very hard. It is like speaking a new language language, and having no time to think about what comes next. It all happens so fast.
As most of the MWSD community ages out, perhaps gender terms will become a concern, but I do not see that happening any time soon.
Rich Sbardella
Stafford, CT