Does NSA, or any another "higher than the batter's head" code, claim that a ball that does not travel higher than the batter's head must be a foul tip? (Answer: No. The phrase is in no way a defining element.)
ASA removed the wording out of recognition that a ball could be lower than the batter's head and not be foul tip, and also that a ball could be higher than the batter's head and still be a foul tip.
Therefore, the phrase was useless and served merely to confuse.