Discussion: prenuptial arregements are a good idea?

Why should we do a prenuptial arregments? Are they necessary? Do they make couples or separete them?

On the one hand this prenuptial arregements separate the couple because they look for their own security and maybe they don´t rely on his partner, also it isn´t look for the future of the couple. It seems like they are single and their only interest is the security of their own economy.

On the other hand it is said that it isn´t any problem. It is only a paper and just this. They do it because it is a garanty for the couple and also for their future children.

In my opinion prenuptial arregements shouldn´t be done because if you don´t rely on your partner you musn´t marrry him/her.