Dave Maine, I agree with you. But certain professions, such as police work, where they need to digitally zoom in on a car's license number is an immediate need. It can't wait for post flight photo processing in some cases.Critical image work always involves post processing to get the luminously and chroma accurate. Likewise cropping. If you have the entire image recorded, you can easily crop it to what you want. It is really not necessary to crop in camera with a digital zoom when you get better results in post processing.
A true zoom would be helpful if you need the maximum resolution of the sensor available. Digital zoom does not give you that.