Re: Bowing in aikido
My thoughts are these:
Aikido transcends rituals, symbols, and cultural decorations.
An instructor may skillfully use rituals, symbols, and decorations---such as bowing, testing, wearing gi and hakama, folding a senior's hakama, clapping, ringing bells, burning incense, and so forth---to help students find Aikido, to point to Aikido.
When the student achieves a certain understanding, though, the student sees Aikido's principles everywhere. Consider this passage from the Art of Peace: "Do not fail to learn from the pure voice of an ever-flowing mountain stream splashing over the rocks." What sees the principles in the stream at that moment is not concerned with whether or not the attached body is wearing a hakama.
With that understanding, though, the student should neither desire nor have an aversion to bowing---or to any other of the rituals, symbols, or cultural decorations. If a student begins with this understanding, even if incomplete, he or she can learn the techniques of the physical practice from anyone, even those who have not attained the same understanding.