asset tags - importance

can anyone elaborate on why asset tagging of laptops and desktops is so key to both asset management and desktop support. I have noticed a number of our devices (especially the older ones) the tag has either fallen off, or in some cases the engineer forgot the assign the label before it was issued. Realistically though what is the risk with this to a company? all devices obviously have a hostname that appears in AD etc  If management said we arent going to asset tag any end user devices, e,g desktop/laptop, where is the ultimate risk in such an approach? I am struggling to see the overall benefits in asset tagging and risks in not doing so?