Will-worship is not following commands God gave in singing but instead one follows his own will doing as his own will pleases him.
hypothetical questions:
would you say adding human commands to the scripture that are nowhere found in it, and which directly contradict the precepts given to us multiple times in the Bible, would be "following one's own will" ?
how about making laws like "touch not, handle not!" regarding things that the scriptures explicitly say are good... would that be "false humility and a shew of wisdom" ?