Debugging is not fun when your program is leaking memory and you're not sure why, and existing code tools don't tell you why. Especially if you're writing drivers. Sure, stepping through python code might be fun, but not low level c/c++ code where you're in a call stack that's 20 levels deep and half the time you don't have source for the parts the code breaks or asserts on.
What about the level of excitement you get when you find a bug in an underlying Fortran library linked in by code building tools because of a random header file someone included without thinking too much?
