There has been a move in the last two decades towards modular build programmes which introduce manufacturing flexibility. This build approach sometimes calls for connectorised penetrators.
There is an argument that if the connectorisation were inside the hull, this would make maintenance and replacement very much easier and cheaper, whereas operational preference is to have the connectors external to the pressure hull.
Therefore, the reliability of the harness is dependent on the sealing of the connector to the cable as well as the effectiveness of the mating parts.
Mouldings can also be used to bring multiple cables to the rear of a connector in a way that traditional end bells and boots cannot.