Swindon has been on a decline for decades though. The town honestly haven't had any serious investment in at least 20 years. There have been a number of big employers who have pulled their HQ out of Swindon. If Nationwide closed down half the town would be unemployed.
They were supposed to be having a big brand new shopping center built even with an indoor ski slope. But as expected that flopped when the investor pulled out.
The problem they have is that after years of no investment people travel to Bristol or Oxford for shopping etc, so there's very little money spent in the town.
I live in Swindon, and what you say is all true.. But it is by no means the worst place to live - it is a safe place to bring up a family (expect perhaps a few areas), has lots of nice residential areas, it is positioned perfectly between areas like Bristol/Oxford/Cotswolds/Bath, etc (and yes, thats why people go to those places when they want a nice out).. Not much going for it, yes, but still a lot better than some of the other towns in the UK.