Given the needs of most applications (which don't press either database's capabilities whatsoever), that really is probably the main reason.

I think there is some truth in it though; that and the inertia it currently has.

If you're picking up a framework, do you use the default database or try to do something non-default on top of what you're already learning?

>I find it quite patronizing that you assume the only reason anyone would use MySQL is that it is the default choice.

Really? Defaults are supposed to be sane and the best-fit-for-most-common-scenarios... so it's a little patronizing to automatically assume your project is just so special that defaults are not good enough.

Defaults should be good enough until they have been proven to not be good enough. Don't over-engineer your project.