In answer to the OP, YANBU to want people to think about this before settling down, but YABU to generalise a lot.
Marriage is better for women as a class because it benefits the less wealthy party and that's more likely to be us. Regardless of whether this is true of one's own personal circumstances or circle, it's true of society as a whole. So if we all got married before having children, we as a cohort would be better off than we all didn't. But that's a bad reason to get married if you're one of the significant minority of women who have more wealth than their male DP (though you may still want to marry anyway for other reasons). So YANBU to point out what's true for the majority, but YABU to suggest the minority should also make their choices on the same basis.
YANBU to say that it would be a good idea, if you know you want to get married, not to effectively give away any leverage. It's not about forcing your partner, but if someone knows they won't be able to have babies with you and set up home with you if you're married, their decision process might be different than it would be if you're happy to give them everything they want regardless.
Or it might not be, in which case you need to decide whether marriage is important enough to you to forego babies with someone you're not married to- but either way, it's good for it to be an informed decision. Much better than sleepwalking into something.
YABU to think marriage is always protection, it's not. On average, we're better off married than not, but that doesn't mean it's a substitute for other provisions. You can still end up screwed.
What is not likely to be a good idea is giving up work to be a SAHP for the kids of someone you're not married to, working unofficially in their business that you don't part own, paying utility bills in a home you live in but don't own. No woman should choose any of these without thinking very carefully. But you can be unmarried without doing any of that.