If you create multiple top level elements, you can return yourjQueryobject.get() and return the whole array, which will be flattened by .map.
I think there is a lot of oppositions to land support for this. jQuery has a lot of signatures as it is, and the need to pass an array of jQuery objects is just not something that I've seen come up with any regularity over the last several years of looking at a lot of jQuery code.
Furthermore, there's the issue that creating elements in the .map() loop is not, itself, the most performant way to create many elements - it's wiser to create a string and concatenate and insert it all in one go, if possible.
Even furthermore, you could also do this "within" the jQuery framework by using the add method to push each of the newly created jQuery objects into the jQuery object you ultimately plan on appending.
So between the fact that we haven't seen much of a demand for this before, the added complexity it adds to the method signature, the fact that it perhaps encourages suboptimal practises, the performance implications for already existing signatures like arrayOfDomElements, and the fact that there are certainly ways to achieve this functionality already, I hope you understand where the reticence expressed here and on the pull request is coming from.