We first made our quick-release handlebar mounts out of cast aluminum, the idea being they would match the burly aesthetic of the Evo light and inspire confidence in the hold, but we ran into a couple problems. First, metal on carbon handlebars isn't great, so we had to put a rubber shim in there to prevent scratching, but worse than that we realized we needed the mount to break in a crash before it could damage the expensive handlebars, or the light itself, so we had to design in a "crumple zone" for safety, as it's much easier to replace the inexpensive mount than the bars or the light.

We made the switch to glass-fiber-reinforced nylon, varying the fiber fill content to give us the balance of stiffness while also allowing the mount to bend under impact without snapping, which is something aluminum can't do because it's so stiff. This means the "plastic" mount is actually more robust than the metal mount in surviving impacts, while still being plenty strong enough to hold the light firmly over super rough terrain, and without having to worry about scratching or damaging carbon fiber bars.

Beyond that, GF nylon requires no coating or surface finish, so we can maintain much tighter tolerances to ensure there is no play developing in any of the moving parts, and add features like interlocking teeth to the angle adjust that will actually hold well. Eliminating surface coatings also means super smooth action, and basically no wear at the quick-release interface, so it won't get slack over years of use, and will never wiggle around on the trail. 

We could machine a super crazy strong billet aluminum mount, but it wouldn't be better than GF nylon, it would just be more expensive.