In-laws to most but Outlaws to a few!
Why discuss in-laws before marriage?
In-laws come with the marriage, whether you like it or not. It is like living in Texas, you do not have a choice about the sales tax, and you just pay it.
When you marry, you do not only marry that person you get the entire family. You just cannot ignore that these people exist; you are going to have a form of relationship with them. If only because it makes your partner happy knowing how important they are to him.
Deal with it, your partner did not fall from the sky, someone gave birth to him, loved him, nurtured him and he will not be the person that he is today without those people in his life. Just like you have parents that love and care for you, same goes for him too.