Remember, we are set to lose both Jones and Williams. In a normal year, $8M would be a bargain for Aaron Jones IMO. Howver, its not a normal year and thus it is more of a question of "what can the Packers afford" as well as "who do they have to take his spot?". While I think Dillon is a comparable replacement for Williams, I don't think he even comes close to replacing what Aaron Jones gave the offense. Eventually he might, but to rely on it? Jones has averaged a little over 1500 yards from scrimmage the last 2 years, that isn't going to be easy to replace.
If cap wasn't a concern, few would blink at paying Jones $8M. Question is, where do you weaken the rest of the team and/or mortgage the future to do so?