Interesting point(s). I don't want to suggest that there aren't "universal" dimensions to music--or, for that matter, to sound more generally (thus, to include other animals, and perhaps also plants, as responsive to some of the same auditory stimuli we respond to). Moreover, I'm no Japan scholar. So take what I'm about to say with a grain of salt.
From what I've read, Japanese culture marked a radical transition after WWII and the atomic bombings. Prior to that, Japan was culturally isolationist. After that, Japan, especially the young, passionately embraced the western cultures that had defeated them in the war, especially America. Hence, the obvious and genuine interest in western music among late 20th century Japanese. Some of the greatest "western" musicians of that recent period were Japanese; the Suzuki Method of music pedagogy was developed there; Japanese students are way over-represented in good music academies; etc. etc.
Which is to say that the (recent) Japanese love affair with western music is not necessarily indicative of the "universality of musical aesthetics." Rather, it's historically determined--and historically limited.
To return to the question of this thread, then: if music can be widely perceived as sounding "sad" or "happy" or "profound," then one supposes there must be some objective feature to account for such agreement. I'd argue, however, that such features must be recognized to be culturally specific--that, without "training the ear" (and by that I DO NOT mean going to music school, but rather, just living in an environment permeated by music, and unconsciously, or at least not deliberately, assimilating certain patterns and relationships between tones), the perception of musical "meaning" (sad, happy, whatever) isn't possible. The hypothetical human being "raised by wolves" will not perceive music in the same way you or I do.
And so, if it's true that "music soothes the savage beast," it's not because that beast perceives it as "soothing," but for some other reason (like the "soothing" sound of a gentle rain, or whatever).
Just some random thoughts.