It's not a bad way to build a web interface for a C++ application that needs to be configured over an intranet. It makes tying "click on a button on a web site" to "run an administrator action on my application" very easy, and you can use your Qt muscle memory to lay out a simple admin interface with relatively little mucking about.

You can do all that with CGI scripts or whatever, but if you already have a bunch of C++ running on the server it isn't nuts to use Wt to build your CRUDy admin interface.