I think it's fairly easy to dismiss this feature from the context of specifically embedding posts. If you aren't really generating a lot of written content and doing cross-referencing, it's easy to see how this feature seems like something the casual user has very little use for.

That said, where this feature really shines is when you break out of the blog or content-focused scenarios into areas like e-commerce, where you can now embed products or reviews or recipes or testimonials or anything else you can dream up where previously it would've been very difficult to package that information up in a reliable way and allow for external embeds.

The fact that the embed templates are themselves customizeable on a per-post type basis makes this an incredibly powerful yet simple-to-implement feature any plugin or theme developer can leverage.

To give you something to think about, I'm pretty sure WooCommerce supports embedding products elsewhere. Imagine if you could embed an entire category of products on another site. Virtual storefronts wouldn't be too far off the mark. And to think that making that possible might be as simple as dropping a product archive link into the page and WordPress handling the embed logic, is pretty mind blowing.

I don't think we've come close to fully realizing the potential of content embeds in WordPress yet. I really look forward to seeing how developers leverage this in interesting ways going forward.