pineteam
First the VS mode. Nothing is forbidden off course but some things are recommended. Aversion to VS mode may have it's origin in the fact that in VS mode the speed(global as it is called) protection is a later development and wasn't their from the beginning. Secondly the priority of this mode is VS and not speed so sometimes not an appropriate mode.
As far as command upgrades are concerned there is regulatory minimum, beyond that it is on requirement. Without proper attitude and aptitude mere thickness of logbook is like growing old it just happens. Experience can be what Oscar wilde had said "Experience is merely the name men gave to their mistakes".