What are you paying for when you buy GPL themes and plugins?

Now that TemplateMonster just announced it will be issuing WordPress templates under GPL licensing, here's a relevant post by Chris Lema about GPL themes, why they're so important, and why they might even have a price tag. https://chrislema.com/gpl-themes-plugins/

I've suggested themes may end up costing more. But if these are GPL themes, shouldn't they be free? Here's my take.

Originally posted at The WP Guy - WordPress Web Design