I agree completely, Personally I think that something of that magnitude would be the only way that someone that has not read several of his books would be about to truly appreciate the scope of the world building that Sanderson does. Let us take Final Empire for example (mainly because I am most familiar with his work on Mistborn). Do you think that within, say, two and a half hours that Allomancy can be explained, create depth of character, and be able to tell the story to someone that has not read the book? I fear in a one book = one movie that most of the characters will be left out, Ham would be a background character at most, and if the director is unfamiliar with the full series Spook could be forgotten as well and he will have to be inserted in movie two or three.
Unfortunately, for the movie to be profitable it must be digestible to the masses. For the movie to be made it must be deemed profitable.
With Game of Thrones mentioned, I believe that HBO would be a poor choice for his work. No, Song of Ice and Fire is not a family friendly series of books to begin with but I would be afraid that they may push Sanderson's work in that direction as well.
In my opinion, SyFy does not usually do well with their movies, but I have seen some pearls on their shows such as Eureka, Haven, and Ascension. FX would also be a target to fire at, I must admit to being a huge SOA fan, and they have done well with other series (how exactly do you pluralize that word?) as well.