We've never incorporated anyone's code without their full participation and there's no code in Thesis I would want anywhere near core anyway. Thesis is a triumph of marketing, not technical competence. (In fact it relies on people not being able to question its incredulous claims about structure and SEO.) The few cool ideas it has were done in other themes first anyway. On a tech level, WooThemes is doing far more interesting work. (And they have been involved in core development.)
What's your opinion on that fair use argument? That's the only way I could see Chris having a legal leg to stand on. It seems pretty clear that Thesis is a derivative work, especially given that it extends a Wordpress class[1], but if a theme's use of Wordpress does fall under fair use, he wouldn't be violating the license.
It seems that if you buy the FSF's position[2] that linking from a proprietary program violates the license (meaning that linking is not fair use), Wordpress themes are definitely not fair use. But I'm not sure if that's been established in court.
I don't think this is a case of fair use. There is linking, which in the manner which themes work and are loaded inside of WordPress is very deep, and there is also copy and pasted WP code included in Thesis.
I find that believable because Thesis was a waste of money. I'm more comfortable picking and choosing which plugins and themes I want to use and getting into the code if I have to. Thesis never came me anything faster than I could do with the those things alone. Their most compelling argument to me was the structure/SEO claims which were never well explained. None of my sites, Thesis or otherwise, ever did well from an SEO standpoint, so in that respect I have no preference.
To me it seems like they just got popular because they were promoted on Copyblogger with a huge readership and all of it's partners/affiliates. You can't go to a site about copywriting/SEO/online marketing/Wordpress/blogging without getting hit over the head about how "Thesis is the greatest thing ever".
