I don't disagree with a lot of the things you are saying, but when you add it all up, Stafford is still probably our best, most certain option. No, it's not a slam dunk. If it were, he wouldn't be available.
When it comes to processing, reading defenses, etc., my hope would be that Reich manages him a little better, so it's not all about arm strength and gun slinging. Hopefully a high end running game will take some pressure off of him.
As far as his skills potentially declining, I believe Chris Simms said Stafford has the perfect throwing motion to play until a relatively old age.
Again, he's not Manning or Luck, but you can compete with him. Hopefully you can get 5-7 good years out of him