”Shouldn’t we better teach passengers to leave their belongings, to crawl under smoke, to push other people out if they are unconscious?”
Teaching will help only a little, at best. You would have to train passengers.
The more they’re under stress, the harder it is for untrained passengers to deviate from their standard “leave a plane” program. That includes taking one’s luggage and waiting for other passengers.
And yes, that applies to the life vests instructions, too. Advantage there is, that if you need those, chances are you’ll have minutes to prepare (but often, passengers still will make the mistake of opening them while inside the plane)