I think it depends if you are using cabin like a hotel room. Just to sleep in.
If its just a place to lay your head and get showered and dressed, why bother paying for a balcony cabin. You can use all the ship facilities for sitting around, relaxing. After all thats what the facilities are there for. You could probably do two cruises in an inside, for the price of a good balcony.
But if you prefer a bit private relaxing time, well then go for the balcony.
Its all down to choice.