Because it usually involves doing a lot of things that are unsafe. Take reflection for instance. There is no way to guarantee at compile time that a string whos

Because it usually involves doing a lot of things that are unsafe. Take reflection for instance. There is no way to guarantee at compile time that a string whose value is only known at run-time is actually a real method in the code that can be invoked. To get the level of safety they have gone for they have to disallow anything that could potentially blow up.