You are the LAST person I would think would be THIS irresponsible!
I actually didn't know it was that important, since the brakes worked fine, at
temperatures above -5°C.. and since I needed the bike daily for work, never
dropped it off to get the fluids changed.
I actually ended up without brakes on my kawasaki once, after winter storage
(maybe 2,5 months actually), the rear stopped working.
Bike was something like 3,5 years old at that point, and the guys at the workshop
were shocked with the amount of "junk" and water in the brake lines.