Tint makes the device appear the same color when illuminated from outside light (room light, sunlight). Also easier to sort out, if you know you had a green one and 50 reds on the bench then you can tell them apart without powering them up one by one. Rarely of any use really. Tinting also decreases the light output slightly. Colors LEDs start by creating only one color of light, unlike an incandescent tailling for example which always makes white light and the tinted red filter makes it red.