Tags become most useful when used consistently. The suggestion is to allow a super admin to define the tags which may be used. Spelling will be assured and close duplications will be avoided. Needless generalities will be prevented.
An admin generated tag list should have 2 options
a) admin supplied tags only. Choose from them.
b) admin supplied tags are suggestions but the user may create his/her own
The existing option to require at least one tag should stay.