[pfdietz]

Note sure about your second point there. An LED can be brighter if the diode is driven harder, right? But that can shorten its lifespan. Also, LEDs degrade over time, maybe it's better they just die before they get too dim. There's a tradeoff here between lifespan and user experience, and perhaps between lifespan and energy efficiency.

[Gibbon1]

Yes running the LED's close or over their rated current will notably shorten their life. It's generally true for all components. Lifespan quickly falls as you approach the max rated voltage, current, and temperature. And they compound. Thing to know specs for component lifespans at max rated conditions is often remarkably short, like 1000's of hours.