Renaming special property
I think a general recommendation on how to name properties will be of great help here. Property naming tends to be a total mess. From experience I would probably never create a custom property just named "Creation date" as you yourself would not in the meantime since it is destined to conflict not only with special properties but other possible custom use cases on a wiki. I myself did occasionally fall flat on my face, too. However starters do not have this experience an you cannot blame them at all, so that's the issue I believe.
I have to disagree. In my opinion, Creation date is a perfectly legitimate name for a user-defined property and therefore not so for a special one. There was nothing in that name that suggested it would one day be occupied by a newly created special property. An SMW user can follow any agreement on naming properties or follow none; this is his business. As long as he does not invade the area reserved for special properties (and such area has never been defined), he is right. That's why it would be a good job to clearly separate names of special properties from user-defined ones. An underscore or two as I suggested above would do.