He was the most expendable of the guys because they have a lot of emerging young talent that is cheap.
I'm sure they would have loved to held on to him for a year or two but this is how the business side of football works now with the new CBA. For the money they are paying him they can pay their 1st and 2nd round picks next year.
The Chiefs have a "window", Reid is going to go for it and they have ownership that is supportive.
Raider and Broncos fans are hoping they don't find a good young QB in the next couple of years because if they do they are stacked. Smith will only take them so far IMO. I have to admit that I didn't think Reid would do anything there but he has.