Why Wai Kru ceremony is so important.

In my opinion I think Wai Kru ceremony is doesn’t matter.It used to show that Wai Kru ceremony is organized to remember the virtues of the teachers who taught us in tangible.I think Wai Kru is more of a spiritual issue.If he is grateful he will fell it without any ceremony.but if he doesn’t feel grateful any ceremony he will doesn’t feel anything at all.