Bad Engine Design!
Southwest Airlines flight 3472, 2016. Same engine, same type, same airline, and very similar event, including fuselage damage and depressurization (occurred around the same altitude as well). - one turbine blade release should be contained and NOT explode the cowl.
The fan inlet cowl is not intended to contain engine parts - the fan case does that. Its purpose is purely aerodynamic (to provide 'clean' airflow to the fan face and a smooth aerodynamic surface around the engine) along with acoustic treatment to suppress fan noise. However it's not supposed to fail due to the forces of a fan blade out - and they are designed to contend with the forces associated with a fan blade out event. I'm sure the NTSB, FAA, and Boeing are all concerned that there has been recent fan blade out events where the inlet departed the aircraft. If they were designing the CF56 engine today it would have a completely different modern fan case containment ring.