I was going to report this bug:
Clearly, I don't want the result to be what it currently is:
It's so easy to achieve this behaviour if I wanted it by explicitly specifying the default. It's so hard to remember that this feature exists, having spent yet another 30 minutes debugging my own code until I was reminded of this:
It's very random, why would the first TIMESTAMP ever be special? Why not the last? Or the fifth? What about DATETIME, why doesn't it apply there?
I strongly suggest you remove this "feature," which looks like a bug to me every time I run into it, and it's really not the first time. Users can very easily specify DEFAULT expressions themselves