There is, of course, nothing stopping anyone from buying the source code, and making it publicly available.

IMO the basic premise of the GPL is that users who receive the program/app/whatever may also get the source code, modify it, and further distribute under the same license.

Section 3 of GPL2 states: 3. You may copy and distribute the Program (or a work based on it, under Section 2) in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following:

a) Accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or,

b) Accompany it with a written offer, valid for at least three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or,

c) Accompany it with the information you received as to the offer to distribute corresponding source code. (This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form with such an offer, in accord with Subsection b above.)

Most do "a" but "b" is acceptable and Section 1 even allows for charging a fee for the source code.

At that point, you have the right to distribute it in any way you want -- provided you aren't restricting StudioPress's rights. That means you could actually resell the same theme for a lower price if you wanted and StudioPress would bitch and moan but couldn't legally do anything about it.

That happens with Linux. Red Hat sells their product to clients. They also offer up the uncompiled source code. Others, CentOS, Scientific Linux, etc., take that code and compile it and distribute it for free. The advantage of buying from Red Hat is support and fastest access to newest stuff.

There is absolutely nothing stopping me from buying a StudioPress theme and putting a download link to it on my site, or even hosting that content on Github. It might be poor taste, but there'd be nothing against StudioPress's rights with me doing that.

My biggest issues with GPL was it was written in an age of traditionally compiled languages. It wasn't written for the nuance of web language and the context of what is distribution, what is complete, what is compiled is different and to me, not as cut and dried.

Most of the commercial WordPress theme shops (outside of Envato) do run fully GPL shops. They do this not because of altruism but because Matt and WordPress.org strong armed them into making the decision to change around 2009/2010. Since then, it's become common.

The reason you don't see people bitching about giving up their redistribution rights or the rights on their images and CSS is because most people who buy WordPress themes aren't on HN, they buy a theme, customize it, use it. They don't think about, "oh, I cold resell this same theme and undercut someone else."

You can read more about this kind of thing here: http://www.gnu.org/philosophy/selling.html