I am disappointed that the jersey went to someone who was clearly not the strongest sprinter
Your answer was in the question...
The green jersey is the points jersey, and not a best sprinter jersey.
There is no jersey specifically for the sprinters, but the points jersey is the one most attainable if they consistently make all of the stage sprints and then place reasonably well at the end. It rewards consistency.
If there was a sprinter's jersey, then Kittel should be wearing it for most stage wins on the non-mountain stages.
Your answer was in the question...
The green jersey is the points jersey, and not a best sprinter jersey.
There is no jersey specifically for the sprinters, but the points jersey is the one most attainable if they consistently make all of the stage sprints and then place reasonably well at the end. It rewards consistency.
If there was a sprinter's jersey, then Kittel should be wearing it for most stage wins on the non-mountain stages.