Why don't some sects and denominations respect icons? think about it...?

The ones in modern time who do not respect icons are Protestants, who divorced themselves from the teachings of the Church long ago. That is apparent especially in Mormonism and the Jehovah's Witnesses (by way of example). Both groups claim to "restore" original Christianity, but their idea of restoring original Christianity comes with it their own tradition of refusing to acknowledge the Christian Canon.