There are many reasons for this, the backbone of all of them being hands free illumination. Though this could sound fairly specialized, you'll be shocked with the things that you'll find uses for.
My job constantly has me in dark places, I'm fairly active throughout the year going backpacking and rock climbing, and
I actually always carry one with me, no joke, and it always comes in handy. I have an old army pouch that I carry every day needs in that I can neatly stuff my headlamp into, but you can keep it in your car, next to the front door if you have a place to hang your keys there, or wherever else might be best for you.
There are allot of options out there, from the cheap to the very very pricey, so do a little research before you buy anything.
And see that your life is illuminated...
