A simple question on the partitioner to avoid mistakes

Up to Dapper, the installer marks, as the default option, erase entire disk to make the partition table. Why not add a small question before starting the partitioner to avoid people erasing their hard disk by accident? For example: "Is this machine brand new or do you already have important files you do not wish to lose?" or "Do you have important documents on this machine?" or something of this sort. I'm sure if it is approved, we will come to a good question and list of answers. For this I can tell, working all days answering user calls: They don't read, so we must make everything as clear as possible.