I don't understand the shock. The inclusion of 5 more nominations was obviously to cram in some blockbusters that have no chance of winning, not nominate the next best 5 movies of the year. The Blind Side won't win, but Ma and Pa have seen it and sure liked it. Maybe they'll actually tune in.
I don't think anyone is as shocked, it's more like a sense of disappointment. It's like seeing a family member get out of jail, and you hope they clean their act up - only to disappoint you by stealing money from your wallet to buy drugs. You may have expected it, but it doesn't make it any less heartbreaking.
But you're exactly right, the field has been expanded to entice people to watch the ceremony with mainstream nominations. I personally think it's kind of sad, because think of all the
great films people would not have seen had it not been from the exposure at the Academy Awards (which have turned limited runs into nationwide expansions). By turning it into another Golden Globes, the industry is just simply reinforcing uneducated viewers that nothing really exists outside their local cineplex.