...LEDs get hot

An LED emits light but it hardly emits any UV or IR radiation; the emitted light is cold - illuminated objects are not exposed to heat. LED lighting is therefore ideal for illuminating sensitive objects - for example in museum or shops.
The LEDs themselves (and therefore the entire module) are heated up however by the process by which light is produced. This heat must be transported away from the LEDs.
The life of an LED module depends on the temperature at which it is operated.

The cooler, the higher the lifetime, the brighter the LEDs.