Keith Ray posted a link to an excellent write-up where the author talks about developers thinking that writing code without tests is faster and comparing that to what he calls "process addiction."

Here's the link: Break Your Process Addiction

Jonathan Kohl blogs about the dangers of reckless test automation. He's right on the money and I strongly recommend reading what he has to say.

One thing I'd like to highlight is that the source of the problem is not "100% test automation" itself but the interpretation of it. I haven't heard a single agilist I consider knowing his (or her) stuff say that the goal should be 100% test automation and 0% manual testing. What I have heard people say (and what I've said myself as well, from time to time) is exactly what Jonathan is suggesting: that all regression tests should perhaps be automated but that context-driven, risk-based, exploratory manual testing should be carried out in addition to the automated tests.

Computers are good at finding bugs we told them to look out for. Humans are excellent at finding those we couldn't see coming.