imho marriage is only worth it if one of your life goals is to spawn and raise kids.
the purpose of marriage is to
1. announce to the world (and each other) that you'll be living and operating together as a unit.
2. Via that announcement, a sort of promise is made to poll resources and act as a unit. In this way It better sets (or forces, depending on the situation) you two to work together, especially in this big investment of having a kid.
To have marriage without a kid:
1. it's great that you're together, yeah, but that's not that much different than close bf/gf relationships
2. There's some legal shenanigans like some weird tax cuts, power of attorney shiznits, and next of kin stuffz. Because you're now considered together, some legal affairs are more easily transferrable since you're legally "together"
To have kids without marriage:
1. Tbh it's not that different than having kids with marriage.
2. just the legal shtuff from the previous stuff
Conclusion: You do you. marriage is more like an announcement, and a way for the dumb, deaf, and blind gov't know you're together, should some legal shit come up. It's a tradition that also managed to get codified into law.