I have to say that at one point I really liked the GPL license and the idea behind it. I always thought that it is weird to call it viral.
Consider their statement on WordPress themes:
The PHP elements, taken together, are clearly derivative of WordPress code. The template is loaded via the include() function. Its contents are combined with the WordPress code in memory to be processed by PHP along with (and completely indistinguishable from) the rest of WordPress. The PHP code consists largely of calls to WordPress functions and sparse, minimal logic to control which WordPress functions are accessed and how many times they will be called. They are derivative of WordPress because every part of them is determined by the content of the WordPress functions they call. As works of authorship, they are designed only to be combined with WordPress into a larger work.
Doesn’t this statement come dangerously close to the argument that Oracle made regarding copyrightability of the Java API?