As for Tk, my principle is: if I already picked Perl for a task as it is the best fit, I will use Tk for GUI interface if there is a need; but if GUI is so important for that task, I will never pick Tk, in that case I would either go web, or Java (most likely will switch to C# in the near future.)

"From very limited .NET nodes I consider this to be very unpopular"

;-) Now this is a Perl site, we come here to talk about Perl. It is expected to see "very limited" .NET node, but it is sort of jump to concolusion when you said .NET is "very unpopular". It is impotrant to pick the right tool for the right task, to be able to do that, you have to first realize what tools are available there.