Setting wage limits would go completely against the new free player's policy, i am not sure if this is going to happen.
However, did you noticed that many free players becomes UNH when signed? It didn't happen in every argentinian team, and the reason was that those managers offered more money than their wage budget, the biggest problem here is that player room is not working properly.
If that "limit" would be working, competition would be fair, and user won't have any "surprises" when weekly wages needs to be paid. At least they will have a barrier telling them "be careful".