The question of whether 12TET is "natural" or not is an interesting one, and in my opinion, it was great for a few centuries, but at some point music will move beyond 12TET. Take a look at one of richest websites exploring this question [1], whose author has a different opinion from mine.
As for skipping the 7th harmonic -- i'd say you shouldn't do it. If you scroll down [1] until you get to the "n-tone equal temperament" graph, you'll find one of the nicest ever justifications for 12TET. However, if you added more harmonics to that graph, you'd find that the 7th does not fall anywhere close the 12TET frequencies: that's why we're not used to hearing it, and it sounds the most alien to us.