Sometimes there is a need to get a list of users from the requester to fulfil a request. For example, if someone wants a new Distribution List, you would want them to include a list of users to be in the new list. Or if someone is switching roles, you may want to know who is now reporting to this person.
The only way to do that currently is to use a Text Field or a Text Area. This opens things up to typos and other issues. If there was a way to select multiple users, it would be ideal for this kind of request.