To be fair, I think this April Fools prank was probably known by everyone to be just that. Basing an entire discussion point and perspective on it seems a little off.
I remember playing the original Mortal Kombat when I was around 8 or 9. I didn't think it was particularly 'mature'. I did like the fact that it was using realistic sprites, rather than Street Fighters cartoon-esque characters, and I always loved the idea of a finishing move, a special treat for those skilled enough to find out and then pull off a move that would literally destroy your opponent.
I don't think it's about the blood and gore, I think it's the reasons why there is blood and gore in a game that is important. Mortal Kombat fits because it is meant to be a virtual fight to the death. Madworld fits because it's meant to be about a kill or be killed game show (which admittedly isn't exactly original, however the level of creativity to use your surrounding area to accomplish your spree is original).
In short, it's never about the blood. The blood is just a tool to create a desperate situation in which a player must be lethal or risk being killed themselves.