It strikes me that the issue is amplified by French-speaking politicians and media (both Wallon and Brussels). Independence was not an outspoken issue during the elections. Following fragment from the same author might shed some light, in particular the part in italic:

"The Walloons look up to France: they follow its politics more closely
than their own, watching French films and reading French books. In
return, the French on the whole sneer at their northern neighbours: one
guidebook I have begins, "If you want to hear the language of Voltaire
spoken in a German accent, go to Belgium." "

I would say it it the american model that rankles all the froglidites.

"Belgium can seem like an argument between the more “Anglo-Saxon” Flemish and their French-speaking neighbours".

This is absolutely true.

These days in the Belgian francophone MSM, which are completely infested with narrow-minded political correctness (as usual), you can hear or read that lots of Francophone Belgians are frustrated because they don't understand their Flemish compatriots' attitude, because Walloons have nothing against Flemings and because everybody gets on with one another rather well. This is true: it is not individuals who oppose each other on a personal level here. Lots of Flemings live (and work) in Wallonia and vice versa. 

However, the real problem is that there is one country with two different mindsets, which means that there are two different countries, as rightfully suggested by Marc Mardell.

One is Flanders, which is much more conservative (in the US/UK sense) and more economically aware than the other one, Wallonia, a socialist-minded backward basketcase, making the Walloons the laughing stock of Western Europe and probably the rest of the world.

The Anglo-Saxon societal model is more successful, no doubt. But, in Wallonia, people simply don't get it: the American way of life is demonised. The majority still thinks that abandoning the so-called European social model would be a disaster.

Well, Wallonia is already a disaster and nobody wants it. Wallonia is a real shame and a heavy burden, both economically and politically. Get rid of socialism once and for all. That's where the problem is.

A quote from the comments section of Mark Mardell's article reads,"In what other country would not only the political parties,but even the Esperanto league be divided according to the (native) language of their membership?"

Priceless!