Why is it important to reflect on what we read?

This may seem a little silly at first, I mena you just read it. Big deal, right? Actually in many things I've read, if reflected upon, I've found deeper meanings. I'm not talking about your english teach over analyzing why a write decided to describe curtains as blue, but like allusions or hidden references and maybe a few metaphors for life and death. Albeit I usually find these kind of things in poems, finding something you didn't notice before in a story isn't uncommon and feels pretty cool. Like in the Sherlock Holmes adventure "The Red Headed League" when I first read it I didn't pay much attention to the assistant, but [SPOILERS] as it turns out he was the culprit. After thinking back on it, a lot of the things he did made a lot of sense and had originally escaped my thought. Allusions and references could be hidden in stories too, or if you're really luck foreshadowing, like for example I once wrote a story for class and named the character Richard Parker. I realize this is also the name of Spiderman's parents, but my original intention was to reference Edgar Allan Poe's "The Narrative of Arthur Gordon Pym of Nantucket" who had a character named Richard Parker (and was subsequently cannibalized by the remainder of a shipwrecked crew). Unless you look back on stories you might miss these kind of things and truthfully it makes you feel kind of cool to know you just figured out that in the "Wizard of Oz" the poppy field was alluding to opium (not to mention it adds depth to the tale) because you totally knew that.