In the 80s and early 90s Korat used to have a couple of department stores, focusing on shopping:
Klang Plaza Atsadang (still there),
Newland (near train station, closed in the mid 80s),
Tara (where Bangkok Bank Atsadang is now, closed around the early 90s),
Pata (where Tai Fah Electronic City is now, closed around the early 90s) and
Nor'East City (where IT Plaza is now, closed by the end of 90s).
The Mall, BigC and Tesco Lotus still became successes. Life in Korat just changed a lot. Before there were not so many airconditioned places where one could hang out hiding from the heat. In a tropic city like Korat shopping facilities are not so much for shopping, they're rather hang-outs where you can shop as well. The success of new malls and department stores mainly depends upon blending hang-out with shopping. If your way of advertising resp. your lay-out is persuasive enough to get those just hiding from the heat used to buying there as well, you can't fail.