This is a slap in the face for women's rights!
Joking aside, I think the change to the law in Russia is to do with minor attacks such as one spouse slapping another and being slapped back in an argument. This is where one spouse gives as much as the other, which is rarely something for courts to be involved in. More serious abuse such as punching, kicking or use of weapons or one sided abuse will still be against the law.
I don't think there would be support for a change to the law if it were not along the above lines - Russian women would not stand for it.