It really reminds me of Battletech vs. Robotech vs. Macross. Pathfinder took their material from someone else, profited big time on it, and now the original source is going after them for it.
In the same respect, it's like Digimon vs. Pokemon. Anytime you have a successful story, game, etc. that makes hugely big bucks, others are going to try to copy you and maybe even do it better. Is it right? Should WotC just let other people constantly profit off of their material?
It's closer to saying "sure, go ahead and use our open license that we won't revoke" for YEARS and then once your competition gets good enough saying "oh, yea, now we're changing that". It's a nasty move, and I doubt it would hold up in court.
