Am continuing to read Curtis Roads' book Composing Electronic Music: A New Aesthetic. He has this to say about conventional Western harmony:
A formidable advantage of 12-note ET [equal temperament] over its predecessors was the equality of its intervals. For example, an ET “perfect” fifth interval will sound equivalent no matter which pitches are used to form it; this is not generally true of non-ET tuning systems. Such flexibility means that a composer can write functionally equivalent melodies and chord progressions in any key. It also enables harmonic modulation (i.e., a transition from one key to another by means of a chord common to both). The same flexibility fostered the rise of atonal and serial music and the promulgation of increasingly abstract operations on pitch class sets.
The mother lode of 12-note ET has been mined for 500 years by millions of musicians in innumerable compositions. The tuning is so ingrained that it is virtually impossible to musically express anything new about it. Consider a work for piano; it is constrained by its tuning and timbre from the start. If it is to find novelty, it must seek them not in tuning or timbre, but in other aspects of the composition. This is not to say that it is impossible to express anything new with 12-note ET. However, the new thing is not about the tuning. Rather, the novelty lies elsewhere, for example, in a new interpolation between existing genres, an unusual rhythmic organization, an atypical formal structure, a fresh combination of timbres, a philosophical message, etc.
The pop music industry sometimes manufactures songs that are attractive despite the use of 12-note ET in worn-out harmonic and rhythmic formulas. Yet some combination of elements in the voice, lyrics, audio production, fashion, face, camera angle, lens, setting, hairstyle, body language, stage show, animation, or attitude spawns mass fascination. The familiar melodic and harmonic formula—like the formulaic beat—serves as a comfortable backdrop.