Good question! Wear is just that; the decreasing quality of your glider/gear as it is worn out from use. The choice to handle it this way was purely to align with the words used to describe it and the game mechanics that already existed. You start with 5 'possible' Wear on your glider, and it decreases to 0 over time. At 0, you are reduced to a max speed of 1, and cannot use any of the mods attached to it (until you repair).
I could have just called it 'Quality' and ticked down in the same way as exists, but I wanted to tell players that their stuff needs upkeep to stay viable in the harsh environments of Eridoor. This choice also matches with how the resources are used in the game, keeping mechanic names aligned with how they would be expected to work in the system, e.g. decrease Stamina, use Momentum, and mark Wear all decrease the total resource pool.
Hope that helps explain why Wear is as it is and gives a little insight into the design process behind the game.