But you're welcome to try of course. But if it was that easy I bet someone would have done so already. This is the classic "zomg look at how complex it is, let's just rewrite it from scratch!" and then you discover that the complexity is there because it solves a long list of edge cases.
> Surely that can‘t be that much in the name of security, no?
Meh; in reality, almost no one was affected by this particular bug, and even if they were, you needed system/shell access to be affected. Like many sudo security problems in reality they're often actually not that big of a deal. Of course, it could be improved, but there's a long list of other things that are more impactful.