well, this thread hasn't been posted on in a while so i'll liven it up!
let me just put it that way: no matter how inaccurate it is, or how much a reader can guess about the plot, most people don't know history well enough to be able to spot the inaccuracies, just as most people can't guess what will happen. so they read the book as mild entertainment, then go to see the movie. so, naturally it sells-the book is popular, so people think they just HAVE to read it, and so most of them buy it, then rush out to see the movie. and of course all the companies will take advantage of this popularity to make money. so to reply to "what is the world coming to?" this isn't abnormal, it's normal to make money off something popular, or just use it to get people to look at something.