Where an approach requires that, on an NDB approach the aeroplane must not be flown below the equivalent ILS glidepath, then I see some merit in adding something to the procedure minimum as the approach is effectively being flown using the same technique as for a Precision Approach.
However, where this 'notional glidepath' is not mandatory, then you should be free to descend at not greater than the maximum descent profile permitted by the procedure to achieve the 'real' procedure minimum, converting to visual or a circling approach as the situation dictates. This does require a high level of handling skills such as are only afforded by regular practice; however, most airlines cannot afford this, so the 'lowest common denominator SOP' of making every NDB approach follow the 'notional glidepath technique' has been adopted. Fortunately, in companies such as Dan W's and mine, pilots may still descend to the absolute procedure minima, so if that means manually flying a 4-jet level for a mile or so at MDA, then that's what we do - but only because we practice doing it reguarly. But places where the notional glidepath is non-mandatory are, regrettably, becoming fewer.