Wilson has a knack for avoiding the big hit that his brethren lack. I don't view him as much more of an injury risk than any other QB.
I have a higher opinion of Wilson than most on this site, apparently. He isn't in Rodgers' and Brady's class, but he's still young and he's better than Tom was after three years. Good QBs are so rare and so expensive than I think Seattle would be foolish to quibble over a couple million dollars, particularly when you are dealing with a very long contract that helps you manage the cap.