There is of course an issue of affordability in Edinburgh. I've heard the argument many times: "you get more for your money out of town". Inevitably there's an (unspoken) assumption attached to that, ie. "you need a car".
For those already running cars in town, it's a more straightforward decision, and I've seen many make it. If you don't run a car, then it's frankly very difficult to live in most suburban/dormitory areas. If you're careful you might find somewhere close to the rail network or a main bus route, but even then you will not be as well served as in the city.
Let's imagine you move to the 'burbs and decide to go car free. All your neighbours will be driving to most places. The social pressure to conform will be pretty strong.