Multiple requests can currently only be assigned by setting the category to something particular. It would be nice if there was a way to assign multiple requests to a single user, but preserve the original categories.
You could manually do this by showing the categories in your queue and then only assigning within the category. Of course it would take a few extra passes. The problem with implementing this as you specify is that not all staff is in all categories in most installations. Hence you could end up assigning someone a request in a category they are not in.
I have thought of perhaps having a “fast edit” type queue where instead of checking the boxes and doing a batch you would have an individual set of drop downs on every row. That way you could fast assign a bunch of requests without entering each one. That is just in the thought stage though and I’m not sure if there’s sufficient demand for such a page that it’s worth adding the complexity to the UI.