I'd suggest the reason 'out-of-town' shopping is so popular is that 'in town' shopping became shite. You couldn't park or if you could park it was expensive... Dirty, smelly chav-filled places with charidee collectors sticking their tins under your nose every few feet....
They are now because they are dead, but years ago, before the out of towners, they used to be bustling places, the heart of the town. Yes, the councils f**ked up by charging stupidly for parking and it gave the out of towners the foothold they needed.
You tell me which out of town/supermarket you can go for good advice, quality and service. They are all staffed by sullen teenagers, who know nothing and are paid peanuts to keep costs down, due to the fact that these huge places cost so much to run that the owners have a choice-stock or quality staff. 20,000 square foot units take a lot of stocking and if you have 100+ of them it tells you why now the big boys are struggling. Now is the time to re-launch the high streets, the big boys have got too big and are having to sub-let to other retailers to cut costs.
As I said, people had a choice and they've voted...
Blame the council for the car park charges, blame the landlords for charging too much rent... blame whoever you like...
Given the choice people (me included) prefer to drive there, park for free, buy their stuff, wheel the trolley back to the car and drive off...