Dominant chords actually contain more of an edge as it contains the devil's triad. Anyways, I disagree with the notion that minor keys are only to be enjoyed by adults. It's like arguing that children should not be exposed to any feelings of loss, death or sadness (for example fairy tales). Minor keys give a different mood and does trigger a different feeling in us I think.
I also think that his notion is more or less reflective of the cultural biases we grew up with. Most of us growing up in Western civilizations are simply not "used" to hearing dissonance that's all. Once you're used to it, you'll hear it as correct, cool, beautiful, or whatever your thoughts may be. Minor sounds, afterall, are natural in this world. We can hear it everywhere.
I also think that his notion is more or less reflective of the cultural biases we grew up with. Most of us growing up in Western civilizations are simply not "used" to hearing dissonance that's all. Once you're used to it, you'll hear it as correct, cool, beautiful, or whatever your thoughts may be. Minor sounds, afterall, are natural in this world. We can hear it everywhere.