What makes you think the market won't provide those 3 bedroom apartments? Why should those details be dictated? Isn't the the whole problem causing housing shortages in the first place - local government deciding how much luxury everybody must have, no matter how much they don't want it? Whenever there's a housing shortage, people start wanting to impose even more restrictions instead of allowing the people living there to drive the market with what they really want.
The market is providing 2 beds (one big, one small) because these are acceptable to young professional couples. When babies come (which is often what happens) then the apartment works for a short time, but then confronts the couple with a challenge. The second bed is inadequate, and if the babies are of different sexes then the law dictates that they can't share the room past 9(?) years old.
This causes the couple to seek a house (there are no 3 bed apartments) houses are very inefficient in terms of footprint, and affordability means that most young couples end up commuting.
Government has a role because developers just building things mean that the costs of the development are unanticipated and then later socialised as collateral damage. On the other hand if government manages development then the appropriate stock with appropriate infrastructure (doctors, schools, shops, transport) can be provided at the time and the cost socialised in the transaction and managed. This is economically much more efficient.
