a big pile on money?........how expensive is it to say "this is campaign X, here is a crappy map drawn by jervis johnson....go play now" and then fake the results so SPESS MAHREENS win, no matter what they were doing.
Whilst I cannot claim to be an expert, what I posted is the responce alweays given when that question is asked - it is given by people who work for GW as well as veteran gamers.
It is easy to believe, too. GW has a stable of in-house writers and artists, and a pool of freelancers.
The in-house mob must be paid whatever they are working on - when they are told to write a campaign (fluff, rules, army lists, artwork etc) they go do it and get paid the same as they would if they spent the time writing codices and supliments.
The campaign information is combined into a book which must be printed and distributed. A few people buy it, but not nearly as many as would buy a new codex or supliment.
GW must register an maintain a website for the campaign, and pay someone (several in fact) to mannage and run the campaign.
At the end, all they have to show for it is the cost of that book that no-one bought...
It's just not a viable proposition compared to what they
could be doing. I wish it were.