While it's not to say they don't interact at all, but rather that they form "pairs" that stick together rather than interact with all the members of the group as a whole.
For example Ann and Ryuji riff with each other through out the whole game, but Ryuji and Makoto barely talk to each other.

The writing never explores the group dynamics rather than simply the MC and X character. Shame really when this is a series that focuses on "social links" between people, but only if those people are interacting with the MC.

Persona 4 and 5 needed more scenes like this, the party members interacting with each other outside of their time with the main character. It's something Persona 3 got really right.