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.
HTML5 styled CSS is also *somewhat* easier to read:

```
div#header
div#content .article
div#content .article h1
div#content .article h1+h2
div#footer

```

vs

```
header
section#content
section#content article
section#content article hgroup h1
section#content article hgroup h2
footer

```

(not using advanced selector)

And as keyboardP hinted through the quote it is easier to navigate a page for non human vistors. It adds semantics. But I do agree with you, that sometimes it can be hard to figure out which element to use `section`, `article` or good old `div`. IMO, this makes the semantic less strong. But lets see what happens.