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: 
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.
I think the great failing of HTML semantic divisions such as is that the code to make these work in the real world involves multiple statements to cope with the actual browsers that are in use by real people. The examples given above *aren't real* and, in any case, to read the html5 code you have to recall that a footer is a kind of div. Just calling it a div and giving it a descriptive ID seems to me to be far clearer, even if we forget about the multiple statements that you'll actually need (really, you will. For several years).
Here's an idea. Make the semantic div IDs attributes, like 'title=' and so on - let the modern browsers and screen readers use this info to identify sections, asides and so on and the code will be cleaner. Don't stop calling a div a div, because you can't install new browsers for the whole planet.

```
<div id ="footer" class="someclass someotherclass" semantic="footer">You, the screen
readers and all browsers know this is a div</div>

```