Why don't we treat greed or pride with the same seriousness? It's our social values interfering with our moral values. Something licit in society but morally wrong (like, say, blasphemy) seems less bad than something illicit in society while also morally wrong (like, say, violence in anger).

You can see this with the sin of lust. In some areas, society is sex-friendly and thus liscentiousness is less worrisome. In others, sex is condemned, and thus liscentiousness is elevated to be a killing offense.

Gluttony has been normalized and idealized as a sign of wealth and success for all of human history in nearly every culture

I always assumed it was due to gluttony being typically visible. Reading 1 Corinthians 6:9 and following, for example, you see several sins many sins which are more internal, or at least easier to hide. Sitting in church and looking around at the crowd, you can get an idea on any gluttonous individuals just by their look. Not always, and clearly you can be overweight without being a glutton. This though was why I reasoned we never hear sermons on this particular sin.