[possibilistic]

I've always been curious--what's the use case for the backlit keyboard?

At the surface, backlighting seems largely aesthetic to me; I have muscle memory of my keyboard layout and do not need to reference the keys at all while in the dark. (A huge tactile cue is the TrackPoint in the keyboard.) I understand that there are lots of variables: not everyone uses their machine as frequently or may not have a keyboard amenable to this.

Does anyone here feel backlit keyboards are essential? Why or why not? What is the consensus rationales?

[allegory]

Anecdote. I had a 2011 MBP with backlit keyboard. Never used it once. In fact, the machine ended up with windows on it because MacOS made me want to smash the thing (despite being a Unix guy) and the Boot Camp drivers didn't switch the backlight off reliably which annoyed the crap out of me.

If you're sitting in a place dark enough to need it, it's not good for you staring at the contrast between the screen and darkness so turn the light on.

Plus I don't look at the keyboard anyway.

[Fuxy]

I never understood the turning the lights on bit I found bright ambient environments hurt my eyes more when trying to concentrate looking at the screen then dark environments.

Then again most websites I use regularly have been re-skinned to have dark themes since white hurts my eyes regardless of the ambient environment.

[allegory]

Sounds like you need to see the optician. I had the same trouble and they sorted it :)

[Fuxy]

I tend to use the backlight on my keyboards to align my fingers and when searching for symbols.

I never felt the need to memorize where all the symbols are located since they change locations depending on keyboard type(language) anyway and i can't be bothered to.