Yes, it would be fine to have dynamic templates with all commands.
I managed to display random defaultmessages now by editing the english.aslx:
<dynamictemplate name="DefaultKill">DynamicTemplate ("DefaultKill" + ToString (random (1,3)) , object) </dynamictemplate>
<dynamictemplate name="DefaultKill1">"This would not be nice."</dynamictemplate>
<dynamictemplate name="DefaultKill2">"No, you won't do this."</dynamictemplate>
<dynamictemplate name="DefaultKill3">"You can't kill " + object.article + "."</dynamictemplate>
This must be done for all commands. Do you think, it is OK to do it this way or would you prefer an other way?