If you're in doubt, read on a true story - this happened to me.
I managed to break my left stick of my then-brand-new MP a few months ago during transportation. It was in the original DJI combo bag, in the trunk of my motorcycle. I had the protector already but thought "nah, no need". So the stick was forced out of center to the point of putting a small dent into the outer ring of the controller plastic faceplate. The inner stick pivot bended out of position, totally ruining the left command. It wouldn't return to center and thus calibration was impossible.
Had to open it, break the bent pivot and re-glue it back into position. It was like a precision surgery, the parts are small and tolerances are tight. Fortunately I was able to fix it and even slightly improve the feeling/resistance of both sticks while performing the job. Did a calibration and everything is perfect since then, no issues.
That's to show how sensitive it is, despite being well built (impressive engineering is evident once you open it and look inside). The magnetic sticks can break quite easily. So now I use the stick protector with a wrist band wrapping it all to keep it all tight during transportation. A small hassle and a few seconds more to unpack, but at least I feel safer now.
PS.: Extra tip: if the protector is too tight going in and out of the sticks, wrap a small piece of sandpaper around a pencil and sand a bit of the inner circular part that grab the posts. Mine is now easy to push/pull but the elastic band keeps it locked in place as intended. A velcro band can be used as well.