Lots of low-cost shops compete with supermarkets, those are the ones that are on the high streets and in town centres now. Such as Vape shops, kebab shops, betting, poundlands, £5 pop up clothing shops etc. if you lower rents in areas that are already struggling you'll end up with more of those kinds of shops in a place that's already serving that kind of traffic.
If you lower rents in twee little market towns, you'll just get more of the same shops that already exist for that demographic too because they mainly want to spend their money on shops they had growing up.
The people who spend diversely on etsy style small business stuff, are the middle-class young adults and older families - and they won't go back to the high street unless the whole thing is basically immediately on par with a shopping village/mall or somewhere like London's Carnaby street for looks and experience.