The current behavior with element template with PI Point attributes is to have a default substitution parameter as you described regardless of whether you're creating the attribute from scratch or if you change an element to a template. Your suggestion of changing this default only when changing an element to a template assumes that the PI Point name can be replaced with a %attribute% substitution parameter. We have no data to support whether this is an improvement or not and it would be a change in behavior only for a specific use case.
The default %element%.%attribute% maybe suitable if you have an element name for your asset and an attribute name for your measurement. So for example, if you have an element=pump and an attribute=flow, the current default would result in a PI Point name = pump.flow, if you were to create the PI Point from the element template.
We currently do not have enough data to support a change in this behavior.