In a setting where magic is feared, where magic users should be cautious, and face risks for being what they are, there should be a constant need to be cautious, some of the higher level spells have that element of consequence to them, which is an active change in appearance.
It's generous that we can cancel our own active spells, and its even more so that they included a way to cancel concealment, if more spells could be turned off by command, I think this would actually cause harm to the setting and concept of danger/consequence for those classes.