Well, why don't you avail yourself of the suggestion thread, so that we don't waste this opportunity. Then we can all comment on whether your proposed more realistic training design is balanced or not.
Personally, I love the training system in BB, as annoying and unrealistic as it is. Why? Because it's excruciating coming up with a strategy that can balance winning league games, winning cup games, and training players. And that pain of trying to devise a good strategy makes following its outcome incredibly compelling. I mean we all here probably love checking BB on Fridays, to see if out little guys got any pops. I also really like that the BB training system forces people to interact via the transfer list. It's pretty hard to train all of your own players, so people are forced to fill some of their team needs with the products of other peoples' training.
I've played many sports manager games that have a more broad training method, and frankly, they are all pretty damn boring. Sure, it's nice when my players get better, and more of them get better every training update, but it's very much a "ho hum, yay whatever" event. For me it doesn't in any way reach the feeling of having a BB player pop unexpected.