Isn't the argument also that when tired, stressed, cold, and maybe even injured, it's easier to tell a 999/911 operator three English words you're used to, rather than a string of numbers most people don't have any context for.
And when I said context, I didn't mean that they would understand what those three words point to, but rather they instantly can read those words having read them before. Long/Lat for most people isn't something they have ever used, so simple things like the "-1" might get missed. Admittedly the operator is likely to know that '1.080278' doesn't make sense given the country they are in and will automatically add the -, but it doesn't hurt to have options?