The kind of use we have for the car, an Electric Car would be totally perfect, with short journeys generally of 10 miles or less.I would certainly deem 300 miles range essential. I have driven that distance in what would effectively be a single journey. I'm not aware of charging facilities on board ferries! Cut down the maximum range available and you will thereby almost certainly reduce the average journey length. (It is, after all, the average!) Keep going like that and you might well end up with a range of a few hundred metres!
However, the kind of use we have for the car means an Electric Car would sit unused for most of the time and would be an very expensive lump of motoring compared to a petrol car.
This is the problem currently ... the people for whom they suit best are the same people where it makes no financial sense as their small spend on fuel means there is no real ROI for electric and so no incentive to change. (and 'saving the planet' is no incentive either as there is more pollution created in making a brand new car than just running an existing one)