Each time you put a cycle count on it, it lowers the resale value of your Air. It also shortens the lifespan of both the internal battery and the laptop. Simple way to prevent it, is by buying and using a battery pack on it when needed. I did this, got an Anker prime 27650mah portable battery bank and for any times that I need to use the Air on battery, I run it off here instead so that I don't put any wear on the internal battery. Much cheaper to buy a new battery bank than a new Air.
Just curious why more don't do this?
While I'm going to repeat a lot of what has already been said, I don't really see the point in anxiously worrying about every aspect of our machines for the sole purpose of maximising resale value. If that's your only bag in life, then fine - knock yourself out. But an Apple device of any kind ISN'T a Ming vase or a fabergé egg, it's not for placing under soft lighting for an exposition. They're designed to be used, enjoyed, even beaten around a little. An MBP without a dent or a strange stain in the corner, or a keyboard that isn't a bit shiny and well worn is an utter waste of the 1,900 to 3,600€ that you spent on it. Same goes for the battery, it's supposed to deplete.
The same happens to a car when you drive it - every pump of the piston puts a minuscule amount of wear on the cylinder and the engine in general (and the drive shaft, and the gears, and the tyres, the paintwork, the body, the suspension etc.) and no matter how often you bring it to the car wash to make it look new, it isn't. It's slowly wearing away, like us... Accept that, and you'll be happy.