My reasoning for "yes" is:
A: It makes your spouse happy, as you mention in the title. ("Boy, a farm like this would be great to raise kids on, huh?" I didn't marry Alex for his subtlety, that's for sure.)
B: You get a Steam achievement for it on the PC! A surprisingly uncommon one, at that!
C: Having kids makes a room in your house with a crib and two kid-sized beds a lot less weird.
D: I admit I enjoy watching them zoom around the house in whatever hat I most recently decided to give them.
E: Your spouse will stop asking you if you want kids so you don't have to hit that prompt every couple of nights. It's literally less effort to have them!
I do legit hope 1.5 gives you some sort of alternative to the kids' room if you decide to go a child-free route, even if it's not one with more space to not give a mechanical advantage to the choice. But for me it was like... "I've got a few reasons to do so (mostly B I'll admit), and it costs me nothing, and my house isn't so cluttered that they will ever force me out of my way more than, like, two steps at most so sure, why not?"