So, advertisements then don't contain a detailed summary of the design process.
No- some do. What I meant is that it is rare that a company will do an advertising release of that size (more than 20 or so pages) in print.
Oh, so movies, and TV shows never do books/documentaries about the making of their creative projects? Serenity Visual Companion, and the DVD documentary Done the Impossible are prime examples that this happens in written form.
<edit>
Well, if making-of material is an advertisement, then I guess you haven't been paying attention to the amount of advertisements people pay for.
Most "making-of" material of which I'm aware has been released
post-release of the subjects they cover, making it a product in its own right and not a preview of an upcoming product.
Reviews & retrospectives stand on their own, meant to tap into an established money stream.
Previews are ads hoping to generate interest in a new product.
The previews in Dragon Magazine weren't free. You had to buy the magazine. Spread over 12 months, how much did that cost?
The cost of the Dragon previews depends upon how Dragon actually handled them:
1) If the magazine price went up, you ate the cost, unless you were a subscriber whose price was locked in.
2) If the magazine price didn't go up during that time and the previews were in place of normal magazine content, you ate the cost.
3) If the magazine price didn't go up during that time and they were in place of existing advertising space, Dragon ate that cost unless their ad rate also went up.
4) If the magazine price didn't go up during that time and they expanded the issues (added pages) to cover those previews, Dragon ate that cost (potentially including increased shipping costs) unless their ad rate also went up.
(These strategies aren't mutually exclusive- Dragon could have blended their strategy, raising the price a bit, raising ad rates a bit, sacrificing some articles for space, and expanding the magazine a bit.)
Don't get me wrong- ultimately, unless the advertising costs are written off (adversely affecting company viability), the consumer pays the price of advertising since it gets figured into the final price of the product advertised.
But actually charging consumers for a product that is an advertisement? That's pretty bold.