2007 x5 inside of headlights scratched? why?

[Ron07x5]

I just.bought this well kept 2007 x5 with 107k miles. A significant cosmetic issue is the headlights the clear plastic on the inside not the outside appears to have fine cracks all over.that looks bad when the lights are on. So is this a common design problem? Did bmw fix with newer part materials? Why has this occurred to the inside.of.the headlights? At some point I may seek to replace the headlight housing but at about 1100 each from bmw I would like to know the problem will not.return. I have the bmw.service records .on the car and noticed the prior owner complained.to bmw.service years ago when it was.under warranty but they didn't replace.them. what gives?