Having more shops in Pelican Town makes no sense from an economy standpoint.
In fact, Joja having a supermarket in Pelican Town already makes no sense at all.
I have lived in a village with around 40 citizens before, and all we had was a church, a bar/restaurant and a local supermarket (yes, we had no school).
For everything else, you had to go to the nearby cities.
Pelican Town already has too many shops for its size.
I know that they are required because, unlike in real-life, you cannot simply add several bigger cities to the videogame to make it more realistic.
What would be nice however, is if more villagers get added to Pelican Town.
The map actually has quite a large amount of dead, unused space.
In the Stardew Valley Expanded mod for example, this space is used to add more villagers.