I find it odd that people would be against blood when Ninja Gaiden is what it is. Not to mention that I'm fairly sure blood was prominently featured in quite a few of the DOA4 endings at least. It's not like it's completely out of left field.
It's not really the blood itself, but more of the fact that while DOA had some some obvious "if this was real, the fighter would be dead period" moments, it was never all that brutal so the emergence of blood and even more obvious bruises rubs people the wrong way.
It would be like if Street Fighter went back to SF2 where you can see the fighters visibly puke and have blood gush out, people would think SF is trying to be like MK but SF had that in it's roots.
It doesn't help that DOA doesn't really have that many punch-able females in it and for those who do want to deck Marie Rose or Kasumi in the face, there's plenty who feel that it would be way too much to see their favorites nearly looking like they've been beat to shit.
You have to look at it from their perspective. Some people may even have this problem with the male characters getting their shit pushed in, I wouldn't be surprised if people turn angry that Ryu Hayabusa can come out of a DOA match looking worse than he ever did in any NG title.
