I also don't see problem in using 7 guys for crucial games. But for entire season, there should be some sort of negative effects for using only 7 guys. Cause now it can be minimized with psychologist/massagist combo
My only gripe is minute management for trainees. This 48 minute requirement probably got copied from Hattrick manager game and in football it makes sense that players play entire game, but in basketball - it doesn't. Now we require 45, 48 or 40 minutes, but maybe with this new garbage option we could reliably achieve certain minutes (36 for example), regardless of game outcome or foul trouble or opponent forgeting to select roster. And that custom amount of minutes would be universal to ages and there would be no need blank lineups or playing trainees full game