We are looking at updating our version of Django in the next year, and I am quite happy that we have a battery of unit tests that test how the features of the current version framework work against our code. I will be a lot more confident about upgrading versions because of what might appear at first glance as 'wasteful unittests'.
Also, as a rebuttal to the author, how can you expect crappy developers who write crappy tests to write good code?