K-Mart and Walmart had a model which was a "bigger store" than Sears and Montgomery-Ward. They used brand names at a discount rather than their own brands that were the staple of Sears, for example.
When Walmart moved out of just rural locations, it used much larger stores, taking advantage of the availability of unknown Asian brands to be able to sell at "better prices".
Remember, Walmart was a "modernization" of Woolworth's "Five and Dime" stores. And K-Mart was the big box brand of Kresge's. Bigger, more stuff. And that model replaced little town stores where customers had to ask for the merchandise which was behind counters.
In every step of this retail transformation the old guard has not been able to transform and found that their brand was hampered by an image of being old and less attractive.