Many forget that WordPress became so popular and so quickly at least partially because of the numerous people that started creating premium WordPress themes that were not GPL and promoted the platform heavily.
If WordPress was stuck (like other CMSs) with 10 free themes like Kubrick - it would be a niche product right now that not many people would know about.

In the end most end users don't care about the license.
They see shiny. They want shiny. They pay some money and get the shiny. They have no interest in sharing, torrenting and other stuff.

Now when WordPress is number 1 - people tend to forget and give credit to the "pioneers", if you can call theme developers that.
Sure, many developers earned (and still do) a lot of money out of this - but still, don't forget the people that popularized it.

P.S. I think it is wrong and somewhat condescending to claim that GPL completely negates the concept of morality and wherever something is ethical or not. Using a stolen credit card (which results in a chargeback + penalty for the author) to buy a GPL product and then sharing it on blackhat forums - there's nothing ethical about that.