Most women don't enter into marriage thinking about benefits. It's more that they become disillusioned after they enter into it and start asking themselves why they are putting up with the unhappiness.

Fewer and fewer young women want to marry, and I am quite sure that it's because they are beginning to ask themselves if it's worth the effort. It's easy to say that they should just do it, anyway, but I doubt that will motivate them.
If we can't describe what net-benefit marriage will bring them, then we might have to admit that it brings them none.