True, but just look how easy it is done with f.e. Services<->SLA, Customer User<->Services (which would better be Customer Groups<->Services) and most of all Criticality<->Impact<->Priority. ITSM should be configured by manager through web Admin rather than system administrator through configuration files which is a Perl modules.
for the CustomerPanel you can arrange this combination with ACLs based on the CustomerID or any other CustomerUser details saved in the CustomerUser Backend.