Mike and I were IMing tonight, and I asked him if he knew why manga creators published their blood type. He didn't know and suggested I post to the blog, so here it is.
Just peruse any of the manga creators on animenewsnetwork.com for example (i.e. http://www.animenewsnetwork.com/encyclopedia/people.php?id=32616 which I just picked at random). This site is full of this type of detail. I mean, I know it's a valuable piece of information to know about oneself (I should find out my own), but why do these creators post this data? It's on some of their personal web pages as well.