Wizards tried to change their license so that all third party material (books, virtual table tops, anything using the srd) was treated the way videogame mods are, and charge 30% of revenue (this was ogl 1.1). Players unsubscribed from the subscription based en mass, and their largest competitor (paizo, who owns pathfinder, and came about because of the last time they tried this) created an equivalent of the Linux foundation for srd licenses, and sold 8 months of product in 2 weeks.
Paizo basically exists to take advantage of bad moves made by WoTC. The cancellation of their license to print Dungeon and Dragon magazines being the inciting event for the company to release its own product, and the disaster that was 4th edition being the rocket fuel that launched it. Pathfinder, a derivative product, was more popular than its parent for a couple years!
