Some times I think they let things be OP on purpose. New class came out that you get with DLC and somehow every time it was the new OP thing for many games.
Other times, they seem to just adjust lower place classes or styles hoping to attacked a more balance between the community that sometimes lead things to being way more powerful just to attempt that.
Balancing always looks like an interesting issue. It can be a way to shake up players base's lack of diversity in it while also encouraging sales.
Always great when players find something in a way that was not intended but is not also consider an exploit either. I've seen in some games like Diablo III some times they leave that situation that lead to something being overpower in for season other times they try and remove in a short time span if.