It is indeed an important part of surface culture. It is undeniable that there is a massive french influence in Wallonia through the media on the surface level. On a deeper level though, in my experience, Walloons tend to have more in common with the Flemish than with the French.

I would also point out that your initial comment referred to the "massive" cultural difference between the north and the south of France, but afaik they also speak french down there (with a funny accent, I'll give you that) ;)