2015 Yamaha R3. Purchased 8-20-2021.
Ce rating isn’t recognized in the USA and doesn’t mean anything at all other than uniformity in European standards. All products have it made thereThe padding is not a protector. It won't save the spine or the ribs from breaking on impact. CE certified back and chest protectors are not expensive to buy. The jacket has already pockets for them, so...
To answer the question directly, almost everyone I know wears back protector. I've never heard anyone wearing chest armor except for myself. But who cares what everyone wears. I care about my personal well being so I wear chest protection. I also wear proper CE certified motorcycle boots without exception or excuses on every single ride. Many riders don't do it though.