There has never been a printed, officially licensed RPG of Harry Potter. Because of this, the world of RPGs has taken a devastating blow. An entire generation of future gamers was lost. How many 12-18 year olds do you know that play RPGs? It's likely not very many. Gamers are like comic collectors - the average age keeps getting older and older because new blood isn't being introduced. Do you have ANY idea how popular a Harry Potter RPG would have been in, say, 2005? We're talking Pokemon CCG at the height of the frenzy here.
They could still release one and it would still be wildly popular. As evidence of this, you can check out one of the DOZENS of online HP RPG games that seem to be less than *ahem* properly licensed. The eye of the general public is moving on to newer things and Harry Potter has run its course for the most part.
The sad thing is, the world of Harry Potter is absolutely PERFECT for an RPG. It is extremely well detailed in the novels. It has that perfect "sandbox" feel like Star Wars. There are so many stories to tell in the HP world! Really, we only saw one small story in a vast world. What about wizards in other countries, even America? What about wizards in other time eras - say, 1,000 years ago?
I find it almost impossible to believe that nobody made a serious grab for these rights. I mean, I can find Harry Potter's face on a lunchbox, theme park, and even Legos. Certainly there have been plenty of OTHER types of Harry Potter games made (board games, video games, even a CCG). The licensing rights can't be THAT outrageous.
Somebody, get on the ball and make this happen. It is better late than never. And I REALLY want to yell, "Avada Kadavra!" as I roll my 20 sider JUST ONCE!