Higher outputs tend to dim bulbs faster, so some people start with a dimmer setting and as years go by increase the dimmer (You would have to check the half-life spec of the light - the time in (usually thousands) of hours it takes to go down to half the light output (that's a 1 f-stop in a camera)
I would think that unless you watch in a room with open windows during the day, you might be able to dim the backight for pleasant viewing in a home setting. That's another use for a dimmer too, if your room has windows and daylight comes in, during the day you can increase the backlight and at night bring it back down.
One minor side effect of watching dimmer images (like in theaters) is that the eye perceives the motion of grain a little less too
In any case, the backlight should be adjusted to your surrounding viewing conditions.