According to the entry of the Anime & Manga section of the trope Sliding Scale Of Idealism Versus Cynicism on Naruto, some of its fandom wishes Naruto was more cynical than idealistic. What I want to know is if this is true, and, if so, why?

Given that a single fan would count as "some", of course it's true. As for why, some people always want things to be darker. You could ask them why but, honestly, most of them probably don't know themselves so you couldn't really trust whatever answer they gave you.