Jiro Dreams of Sushi was a beautiful documentary as well, but clearly sushi was being put on some divine pedestal. That is the 'over-the-top' part I am referring to.
Both Helvetica and Jiro Dreams of Sushi are trying to communicate, to you, the passion that these other people feel for the work they do.
They're not telling you that you should care that much about fonts or sushi. There is no claim if divinity. They're honestly trying to give you a 90 minute glimpse of the interior life of other people.
There are other documentaries that are much more neutral or even dismissive of their subjects, if that's more your taste. Hospital and City Hall are great examples with no editorial cast. Riligulous and Roger & Me are great examples of a documentarian trying hard to have no empathy.
Documentary films are like nonfiction books: any subject can be fascinating when done well, any subject can be awful and banal when done poorly. I’m not even a huge non-fiction / documentary fan but I’ll die on the hill that telling true stories with depth and passion is much harder than doing great fiction.