If columns could have a 'Hidden' attribute in their column properties like in Forms, then we could have a 'Hide Columns' option in the right-click column menu, instead of only 'Show All Hidden Column' and then no efficient way of re-hiding them all.
Also, some way to distinguish these 'Hidden' columns when they are made visible, by allowing some form of user-selected (conditional?) formatting within the sheet would also be informative/useful.