I'm not saying that memory unsafety is useless or even undesirable, I think the "problem" is that it's the default in "current popular and actually used high-performance languages", which means that stuff that needs to be fast and secure (like web browsers) have a hard time.

Maybe my "most of the time" was too strong and I ignored big domains that I don't know. But for the part that I relatively know (web stuff mostly), safety and speed together matters a lot. The thing is, since unsafety tends to be viral (an unsafe part of your stack can compromise everything), people get very paranoid about "unsafe languages".