And, who wants to go shopping on their day off?!
I avoid town at the weekend as it's so manic, because most people have weekends off and can't use town in the week. I work from home so could use town in the week, but with Stafford traffic that hour becomes maybe 20 minutes of actual shopping so why bother?
Supermarkets have killed towns because towns didn't adapt when peoples lives changed. The internet was going to do the same to supermarkets, but they went 24/7 to fight back. I'm not saying town centres should go 24/7 but if your target market can only come in one day a week you may as well shut up shop.
EDIT: TBH I think towns already lost the fight. They need to offer an experience as well as shops that sell things you don't buy online. You need small restaurants and bars, in amongst little shops not big chain places you can find in any out of town hellhole. Lichfield has it right, Stafford almost deliberately went the opposite way.