There is a bit of truth in the lack of maintenance in the Tk module. When Nick Ing Simmons( Tk module's author) passed away, Slaven Rezsic took over maintenance. BUT, he is just maintaining it, as in fixing bugs.

There has been all sorts of advances in the underlying TCL libraries; especially in things like Theme Support and thread safety, that need to be incorporated into Perl Tk. In that respect, Tk is falling behind. On the other hand, Tk is so simple to use, that is is very easy to reach for it for simple GUI's, like just displaying some text or lists.