Thanks for the feedback on this. Brett also gave feedback on the python-ideas mailing list as below : 

> Two things to quickly mention: one is that type hints have no run-time semantics, so adding them to such a critical exception would be escalating their meaning a bit. The other point is this TypeError has nothing to do with the cause of the exception, so I would say that it's slightly distracting from the cause of the issue.

I am closing this.

Thanks