I agree. If it's desired, use a config setting to make it the default. It was already standard practice in any MySQL database I rolled out to set InnoDB as the default storage engine in the config until it became the shipped default. Like transaction isolation levels, this is something you either set as an administrator for your need, or you let the application setup guide steer you, or you let the application queries specifically set it, if the application needs it. Otherwise,you risk causing real data corruption and loss to existing customers purely for the benefit of being more compliant in your default configuration.

A global and per-session setting is sufficient and more beneficial, IMO, so I think MariaDB took the right approach. If MySQL still doesn't have that setting, well, that's troubling, but I can't say I'm entirely surprised.