Please pardon me for giving a philosophical response to a specific issue question.
The way to keep a car going and be happy with it for the long term, is to not let it run down. There are many parts of our cars, the headlight cleaners could definitely fall in this category, that could be termed unnecessary to repair. We can do without the radio, a rear view mirror or two, the windshield washers, even the climate control. What typically happens if you start rationalizing whether or not a portion of your car is necessary, is that these things add up. First you let the headlight cleaner go, then maybe the windshield washer, then some handle breaks, etc. After awhile you get completely put out with the whole car. New cars are expensive, it makes much more economic sense to repair these little things as you go than to see the car go to an early grave or get tired of it and start over with a new one.
Sorry for the lecture, but I've been there, I'm just trying to share my experience and what the consequences turn out to be.
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in