Please don't be silly. Nobody is every operated by "somebody just out of Med school". A year or so after graduation as a general intern and then starting post-graduate training as a specialist. After that it'll be another two/three years of training/assisting before they're operating under supervision. Nobody operates "on their own" until they are board certified as a specialist.
The training is long and thorough - and in the old days (just like for you guys) it was much longer.
You're absolutely right of course, perhaps I over-simplified my point. However, at some point the surgeon is going to stick a sharp pointy object into a live human heart for the very first time. If it goes to **** you can bet your bottom dollar that the supervising consultant isn't going to stand there and watch whilst you use your 'harder/longer' training.
Similarly, there is going to be a first time that a pilot sits in the RHS in an airliner. Once again, if it all goes wrong it doesn't matter if you've got 10,000 hours - you're unfamiliar with the system and chances are you're not going to be the one that rectifies the problem.
Making pilots gain 1500 hours before such a task doesn't ensure good pilots, it just means they have 1500 hours. Perhaps you could argue it shows their determination, but it doesn't particularly give an insight into their quality. I work with plenty of people who have 40+ years experience and I'd swap some of them for staff 6 months out of uni in a heartbeat.