Currently, if a user has checked out an ArcView license but then want to run a tool that is only available with an ArcInfo license they must exit the application (ArcMap, ArcCatalog, etc.), open Desktop Administrator, switch license levels, then reopen their application. If you are opening a large .mxd file that could take quite a long time. And sometimes the user may close their application to make this switch, only to find out there is no higher level license available, so they reopen the application with the same license they already had and acheive nothing for their time.
In our organization we have a national license server that provides access to almost 40 ArcView licenses but far fewer ArcEditor and ArcInfo licenses. We are encouraged to use only an ArcView license unless absolutely necessary so that the higher level licenses are available to those who really need them. However, because it is so combersome to switch license levels, I suspect that many people simply always use an ArcInfo license on the off chance they may require those higher level tools. If we had the ability to switch license levels (say from ArcView to ArcInfo - assuming one was available of course) without having to close and reopen ArcMap (or ArcCatalog), it would be much easier to get people to use the appropriate license and it would save time and frustration in having to close and reopen applications.
Also, sometimes it's helpful to be able to see what licenses are currently available while you have an ArcGIS application open. Currently, in order to view the license availability you need to close the application, open Desktop Administrator, view the availability, then reopen the application. If you could view the Desktop Administrator without having to close the open application it would be very helpful.