The biggest reason to have the match is the money it can generate for both sides. Its inevitable. The match will create buzz because of the performers involved, but the money really comes from the fact that these two huge wrestling organizations are pooling their resources to put together an unheard of event. When two companies with the money, the resources and the clout that both the WWE and NJPW have, enter into a partnership (albeit a limited one), there is simply no way that they dont make money. This kind of dream match, this kind of unimaginable event, is what draws people to wrestling and sports entertainment. Daniel Bryan vs. Shinsuke Nakamura is like Batman vs. Ironman, Captain America vs. Superman, Muhammed Ali vs. Tyson, etc. It is a dream pairing. One that was thought impossible, either because they were from different eras, different universes, or in this case different companies. Theres an opportunity for the WWE and NJPW to own a moment in time, to etch their names in history by bring these two huge stars together for a match that would change the game. There is no knowing what it could lead to down the road (maybe more once thought impossible inter-promotional bouts), but one thing that is certain, and that is that the performers involved, coupled with the momentous occasion of the WWE and NJPW working together, would bring in more money than not doing so. Who doesnt want to make more money?