There are many things that are trivial to do, except that you need to
look at the whole picture:

- someone has to specc it
- someone has to implement it
- someone has to document it
- someone has to test it
- someone has to maintain it

I know, this above addition wouldn't be that much but weighed against
all the other things that they have on their slate it isn't really
necessary.

If, on the other hand, there was no clean way to check if a type is not
a specific type, then I'd agree, make it a priority.