Why is the restriction on name in class MetricWrapperBase to comply with the METRIC-NAME-RE rule? #1039

Why is the restriction on name in class MetricWrapperBase to comply with the METRIC-NAME-RE rule? If I replicate init by inheriting the MetricWrapperBase class, there may be an inconsistency in the transfer of label_values when upgrading to a higher version. I am using version 0.7.1