>Arent' we taking this a little to the extreme? If I am the programmer, it is my responsibility to see that parameters are passed correctly between my functions.

Wouldn't you have to validate the "parameters" at some point? What's the difference, in terms of efficiency, between validating each value in the calling program before you pass it as a parameter, and validating each parameter in the called program?
I agree that it would be a waste to do both. But many times, there's more than one programmer in a team :)