Yes, you must write naturally (and succinctly) in 2016, but if you have no idea the keywords you are targeting, and no expertise in the topic, you will be left behind those that can access this experience.

You can just ‘write naturally’ and still rank, albeit for fewer keywords than you would have if you optimised the page.

There are too many competing pages targeting the top spots not to optimise your content.

Naturally, how much text you need to write, how much you need to work into it, and where you ultimately rank, is going to depend on the domain reputation of the site you are publishing the article on.