The conventional wisdom is that no one reads help (online or otherwise). I'm wondering, would people read a manual if it looked more like this one? Have manuals gone out of fashion, and perhaps come back in style again... or are they something which never worked and never will?

Another interesting issue around help -- people often think that if something is really well designed, users won't ever need to get help. That's true for the most part, however there are important exceptions. When your product enables users to do something which they've never been able to do before, you can't expect that they won't need some help understanding what it is. Groundbreaking stuff will probably require some explanation. The original mac is a good example.

This leaves me curious what proportion of this documentation a. is necessary, b. used to be necessary, but isn't now that computer are a bigger part of everyone's life, or c. was never necessary.

It's also assumed that people who haven't figured computers out yet never will. This is a major problem but is usually just ignored.

Photos of people using the product are powerful images. But , in order to make a similar manual for a web app today, what demographic you should use? It must be like a Benetton ad?

It never hurts to have diversity in your marketing material. And by that, I mean women and black people.