Major = happy seems like a lesson for really young kids that somehow got internalized by a lot of people. It’s so bizarre. In a major 7 chord, the 1 to major 7 interval is quite dissonant… Never mind that a major 7 chord has a minor chord in it, and a minor 7 chord has a major chord in it.

I tend to think of things in consonance vs dissonance, and different colors for chord qualities and voicings. Where the goal is managing contrast/tension and release.