The government trying to predict demand, and students deciding to enter professions based on said predictions, is risky and is why central planning is inefficient - we simply don’t know. It’s better to wait for the market to demand something, show increased prices, and then let the market solve it.
Similarly, perennial shortages now of employees in XYZ profession are always because pay is too low to match the undesirability of the job, or the government is preventing new entrants (i.e. we need more doctors but licensing and the monopoly on training doctors).