Wasn't the reason for "no magic shops" simply an artifact of the edition? After all, Greyhawk and Forgotten Realms, at the time, didn't have magic shops either. No setting had magic shops in D&D because you couldn't by magic items by the rules.
I have to admit, I strongly disagree with the idea that DL is a low magic setting. The heroes of the lance were absolutely dripping with very powerful magic items, up to and including artifacts, by relatively low levels. And the modules were filled to the brim with magic items. One module, and I can't remember which one, I think one of the later ones that had a collection of short modules, had a pool that granted +1 to +4 permanent bonuses to any non-magical item put into it. Granted, a magic item put in would blow up, but, them's the breaks.
I think there was a very large shift in how people viewed the setting starting around 3e era (ish).