I was 10 when DS9 started.
I didn't like it because I disagreed with its philosophy. It was not too complex for me, it was not over my head. I just wanted Star Trek to be optimistic. I wanted everybody to be willing to listen to reason, and I wanted humanity to evolve. I wanted spatial anomalies and evolved human philospohy, not a bunch of greedy ferengi trying to buy stuff and dirty humans falling back on their animal nature without their creature comforts. That is why I only watched DS9 sporadically and didn't even see half the episodes until much later when Spike aired it.
It's not a matter of superior taste or greater depth, it's a matter of not giving the audience what they expected.