Because when Pokemon 3ds was diesel announced before black / white 2 they said they would change the series forever. Many believe a new type is part of this change. That and so many people asking for more types will eventually make the developers cave. Making fans happy makes more monies.
As always, the Light type was thought to be a sure thing just because of Reshiram. Before we knew their typing, many believed Reshiram would be Light type and Zekrom would be Dark type. --- [Este mensaje fue borrado al deseo del dueno]
Actually, yes. When Reshiram and Zekrom were released, everybody was sure that they would be Light-Type and Dark-Type respectively. Speaking of which, I have a topic that I need to bump... --- My NIDOKING brings all the boys to the yard: http://goo.gl/ExAoe