Frankly, it's more important to maximise the number of people that understand government advice than it is to maximise your enjoyment of application forms.
The advice is not even necessarily for situations that are partway between factual and pleasure, like a blog post or your example of a news article (or a HN comment!). In those cases it could still be helpful to bear the advice in mind, but without taking it too seriously.
Les Cowboys Fringants display the full colours of Canadian french in their songs, but they're creating art.
The government needs to tell people of all backgrounds that they must do something or face serious consequences. They are not creating art, but communicating important information to busy, confused people.
It's not about banning new words, killing off long words or promoting completely perfect grammar. Nor is it about letting grammar slip.
A good complement to this article is Orwell's "Politics and the English Language," which talks about how people might use long, complex words (like those in the Words to Avoid list) to seem more important. That's the other side of the "variety" coin. The reality is that a skilled writer can walk that fine line, but most people are better off keeping their word choice simple and direct.
But let us go deeper and ask: how did importance become associated with longer words? Was it perhaps because important and educated people used them, since they carried more precise and specific meanings?