I have found out that unit testing is great if you use it sparingly, that is only use it on public methods of public API. So, if I write server-side software, I unit-test only facade methods that are invoked by clients. And I always run the tests before committing new version, which is a pretty good safeguard.

It has saved me some headaches - especially when software grows in size and you simply cannot predict what impact even a simple change can have.

Anyway, I wanted to say that I agree with most of what you said :-)