I don't know about over-rated, under-rated, or just right. I think that if safety is high on your list of priorities, but you still want to ride, gear is right up there with proper training, maintaining situational awareness, good bike setup/maintenance, regular practice drills, skill implementation, and visibility.
I don't wear ATGATT. Most people in this thread who have claimed to wear ATGATT, IMO, do not. There are a few other items I would like to add to my own gear, of which I wear MOTGIHATT (most of the gear I have, all the time).
I'm wanting to add an upgrade of full hardshell thorax (upper body) protector, a LEATT/airbag (for neck stability) or similar, some compression shorts with CE hip/coccyx/thigh armor, and some full-height moto-specific boots to my current gear (3/4-length HiViz Tourmaster Sonora, Tourmaster Flex pants, various hard-knuckle moto gloves, safety-toed over-ankle footwear, and various DOT FF $100 helmets). I'd also like to get a hydration pack with multiple additional bladders, and one of those pre-soak cooling vests to wear under the mesh jacket on really hot days. A lot of my gear is also for comfort. 'Less sunburn/windburn/deafness/swamp-foot/crotch-rot/exposure/etc. when you wear the right gear. It's also more comfortable not being injured from an off. I fall offroad all the time. Without gear, I'd probably spend a LOT of time being injured.
My bikes are also improved with better tires, better mirrors, better lighting, and a bunch of red/white DOT reflective tape on the sides/rear of my topbox. My lighting is continually improving as I get the funds. I'd like to add braided-stainless brake hoses too.
I wouldn't sweat somebody else's choice in gear or no gear. I barely sweat my own, even though I choose to wear MOTGATT. None of us is going to live forever anyway. Carry decent medical, disability, and life insurance. Then nobody's ass-out if you go splat.