The quality of the rookies is just fine according to me.
Train them patiently and they will be usefull for your team and financially when transferring them.
If you can't give them a spot in your team: sell them right away and do something nice with the easy money.
The problem is when you keep increasing the quality of the rookies, the other player's (equal strenght or worse than fresh rookies) market value will drop like a rock.
A lower league manager who has patiently trained a player for a season might find a lot new rookies as good as the one he has trained over a year, according to your (uneven for all leagues) increase in quality.
The higher division teams wouldn't need the lower div teams anymore to buy trained players from. So the lower div teams wouldn't receive the necessary money to strenghten their team to be competitive when promoting.
Climbing the BB-mountain. Destination: the top.