Kissing the koran could be seen as a sign of submission;NOT the image you want to convey.Better by far to have graciously accepted the book but omitted the kiss.
Every act of a Pope is not infallible;he is only a very human leader of the Church originally overseen by the apostle Peter.
JPII’s heart was in the right place most of the time, but he made a lot of mistakes as Pope. Kissing the koran was not his finest moment.