First off another Max Verstappen can never happen due to age restrictions. Second there is the fact of FIA license points that need to be gathered, which also didn't kick in when Verstappen stepped up. Or at least the more dramatic change we've seen in the past year. These guys that do get promoted usually get plenty of hours in an F1 car along with their collective points in the junior series, so they end up fulfilling the requirements needed to race. If that means not going to GP2 so be it.
However, you'd be hard pressed to find to many people that agree with you on the drivers who skipped GP2 to join F1 being ready or capable. The only one I can think of right now (and you still have to wait) is the new Williams driver, Lance Stroll.