I'd like to know why Lenovo puts devices' MAC address on the outside of the box. For security purposes I don't think a MAC address should ever be published on the outside of a box.
In accordance with the question above, regarding the container "box", this is assumed to be a reference to the cardboard box that the computer ships in. The reason the MAC address (and corresponding bar code) is on the outside of this box is for enterprise management purposes. IT admins scan this label to read the MAC address which is used for deployment purposes, such as Microsoft MDT/SCCM. The MAC address may also be used to allow that specific PC onto their corporate network, so the IT admin needs an easy way to get it. When you are talking about an IT admin that deploys thousands of PCs at a time, you can't expect them to open every box and then power on every PC to get to the MAC address which they need before they can do anything else.
From a security perspective, every time you connect to a network, your MAC address is broadcast out to your subnet. In addition to this, MAC addresses are sequential and predictable. For example, the W541 that came out of Lenovo factory before yours, and after yours, you can guess their MAC addresses. So while MAC addresses are unique, there is nothing random or secure about them.