Protecting a wire linked to a power supply
The power supply that you show is not meant to be used standalone in a portable manner. Instead it is supposed to be placed inside of some type of enclosure. In an enclosure the wiring to the terminal block on the power supply would be harnessed and secured in some manner so that it stays in a particular location and does not freely move around. The securing method will vary by application but could include the use of P-clamps, self adhesive pads with cable ties, or even special hold downs integrated directly in the enclosure design. 

When done correctly things like the AC power cord will be retained through the enclosure wall with a strain relief or plugged through an AC inlet module. The enclosure can the be moved around without concern that the internal wiring is being flexed, tugged or subject to breaking. 

There is also a safety aspect to this too. An open power supply like you have shown leaves open access to AC terminals that can be touched by fingers, tools or other loose bits of hardware or wire. This can be dangerous to the health and well being of the user. There are a whole set of rules for safety that must be followed if you are to apply for a product to be UL, CE or CSA certified. A proper enclosure is a fundamental part of this.