The default time format (%R, 24-hour format) and date format (%A %x) are not good enough for some locales. It's better to be part of the translation project so that it can be changed for each locales.
Created attachment 6142 Make defaults date/time format translatable
André Miranda referenced this bugreport in commit 4de767e604c2fcd063282ef051c224b9e87661e7 clock: Make the default date and time format translatable (Bug #9637) https://git.xfce.org/xfce/xfce4-panel/commit?id=4de767e604c2fcd063282ef051c224b9e87661e7
Yup, I would say that makes sense.