Question: Don't kill me just yet, I'm asking out of pure curiosity.

Elements like `<section>, <nav>, <article>, <aside>` etc all seem completely pointless. Sure they make everything have its own little place (and seo'd)... but it **is** possible to over-organize things. There are some cases where things don't fit in any of the categories too. It also increases time spent trying to code these things. I just don't see any real purpose for moving to add these new elements.

What do we (developers and people who view the webpages alike) have to gain from adding them?

Answer: 
These elements are important for things like screen readers for the blind and eBook readers like Kindle. It helps them know what to show/read and when.
Allowing heading scope is the main benefit of `<section>` and `<article>`. See <http://diveintohtml5.info/semantics.html#header-element>.

Briefly: in HTML5, it’s much easier to mark up an outline of your document (which is useful for screen readers) without worrying about whether to use `<h2>` or `<h3>` or whatever (which gets really complicated when you include components in different places on different pages).

They couldn’t have done that with `<div>`s, because there are billions of web pages that have used `<div>`s and headings already, without necessarily intending heading scope.

Admittedly, `<section>` and `<hgroup>` would have been sufficient for this purpose.