No, it isn't weird at all. Just because pain is a mechanism created by biology for us to survive doesn't mean that the mechanism was created well. Biology is flawed and the pain mechanism is flawed as well due to it being able to reach extreme amounts that can cause suicidality
I wouldn't say it's a flawed mechanism -- it would never have evolved to be this intense if it wasn't necessary for our survival. And if the pain itself was the problem, we would have died out a long long time ago. It must be our rapidly expanding condciousness, and the fact that chronic pain didn't exist before civilizatiom because you would simply not have made it for that long if you were sick or injured anyways, so our brains never had to adapt until very recently.
It's a double-edged sword though, that's for sure.
(I wish there was more literature on the subject. It really helps me sometimes, thinking about pain in scientific terms.)