Lego failed with Castle in the late 90s. Fright Knights, Knight's Kingdom, etc. It was not good and I would assume it sold poorly as it should have.
Bionicle supposedly sells well. MegaBlocks has a strong medieval theme right now. Maybe LEGO doesn't want to compete with MegaBlocks in a theme where their last few attempts had failed and instead wants to market a product line they think will sell so they can make some money and have something relatively unique in the market.
Of course, I won't buy it if that is what they are doing.
