We could certainly play the 'what if...' game all day.
The backstop is proper monitoring and a thorough briefing of threat and error management. If the aircraft enters an undesirable aircraft state, stop looking down at the TV screens wondering what happened and fly the aircraft.
Your comments insinuate that we program the FMS and then sit back and let the plane fly whilst the crew high five and mentally stay on the ground. That's simply not the case. VNAV is a flight management mode, nothing more.
Finally, what's the cleared altitude on the departure, not the initial step? You say setting a non-cleared altitude is incorrect, so define the cleared altitude.