I use them and will continue to use them. I get replace at 3 years or if the bottle is under 3 years but has done 2 full winters of use. I use hot but not boiling water, don’t overfill, expel extra air and use a cover so there is a barrier between the rubber and my skin.
I’ve had a wheat bag combust in flames a while after being taken out of a microwave so I’m not too fond of them but some of my kids prefer them.
I’ve also seen pretty much every accident known to man over the years but would never tell people not to walk on the pavement for example - had quite a few people die after cars lost control, mounted pavements and hit them. You just need to be sensible about things and accept there is risk in pretty much every single aspect of life.