I always put two pillowcases on my pillows, one facing one way, the other the other way, so that the zipper is never exposed, nor is any part of the real pillow. Having two cases on there makes me feel like the pillow is protected enough that the fact you can’t wash pillows isn’t a problem.
Saturday morning I woke up and my pillow only had one case on it. Somehow, during my sleep, I managed to pull off one of the pillowcases. The inner one. At some point in the night I was able to pull of only the inner pillow case but leave the outer one on. WTF?