One weakness of the series is that Ron has no great interests and passions. (Yes, many real school children don't. If we wanted realism, we could always go watch a playground.)
But it's not cut-and-dried. The supporting characters need life enough to convince us that the world goes on about them without reference to the main character, who is merely the center of the story, not the world.
And not so much that they interrupt the main plot and cause it to drag. It is, after all, just another form of local color.
Making it multi-POV doesn't solve it. After all, most of the other points of view will revolve about the plot elements even if their lives don't. The trick is trying to show that when they talk about the hero on stage, it's not because they don't talk about anything else.