I think it's highly dependent on the type of person, or family. For example I have had to help many people track down their documents which are somewhere in a download or documents folder. I, personally, am not the kind of person who sorts my paperwork into folders. Neither, like some people, do I organise every single e-mail into a folder. Gmail has understood this well, and makes it easier to find what I want. I find it much easier to make sure I know _when_ something happened, I make sure I e-mail myself notes, and copies of documents, but most of the time it happens by itself anyway, so I can search for them in Gmail. For example if I want to find some paperwork done when we moved into a new house, I can track down the date in Gmail, and know in which box to go dig it up. Most of the time what I need has an e-mail record somewhere.

That said, I strongly support allowing people to approach the problem from both sides, chronological with good tagging/searching or being able to organise things into folders in a way they like. People work in different ways. However, I think the default is to be disorganised, and the best way to deal with being disorganised is to keep it as simple as possible.