Now a days compliance test for any product or service is becoming unavoidable. Provide some genuine reasons that can prove that is really an important job for any service.
Compliance testing certifies the product meets minimum documented requirements.
These requirements are available generally for broader group who may like to use your product assuming the product meets documented requirements. This group will be interested in checking compliance first. (and so it is important to have compliance report ready)
However compliance testing generally do not throw light on general software quality or defect density. You will need to plan normal test cycle for the product to ensure overall software quality.