A compromise could be allowing non-played families to have one baby without a crib, and then needing a crib to have more. Give us an announcement "so and so just had a baby, they need a crib!" so we can go and edit their house if we want them to continue reproducing.
This will inevitably lead to population decline. Two parents = 1 babby means each generation, without intervention, the population halves. Eventually the only thing left will be playables who are all so intermarried incest is the only option.
I disagree. It's the player's choice if they want the population to decline, and if not, Solmyr's suggestion means they would know which households to provide cribs for and when. This would make it easier (less hassle) to avoid population decline. Maybe it's possible to go further:
A warning when two sims start trying for a baby: "X and Y are trying for a baby... they're going to need a crib soon if they keep that up." Nice to know these things anyway.
Then when the baby pops, if a suitable spot with sufficient surrounding space can be found in the house, a crib could be spawned (and money deducted from household).
Otherwise the player can get another crib warning. If that's ignored, after a couple of nights of the baby sleeping on the floor, the social worker does their thing and takes the kid...
Then there may be a better home (with a crib) available, otherwise it's a drive up to Riverview with a sack and a bunch of rocks.