One can be content in the event that offspring do not provide (for any number of reasons), but also aim for it as a potential benefit (without necessarily restricting your kids).

It can be as simple as having younger people to spend holidays with, or maybe take you to the doctor once in a while, or give a helping hand for a home improvement project.

Of course there are no guarantees, but it is nevertheless something people hope for, and there's a very wide continuum with lots of things above "nothing".