I know there was a similar feature request (" submitted back in 2015 but I want to express a fresh take on this and see if we can get the votes needed to push this through. First, I believe the behavior described in that previous FR no longer applies anyway.
Today when you create a list CP the default is None until a value is specified. While the values are still sorted alphabetically I think it would be extremely valuable, at least for me, to be able to still select a default value. The goal would be that when a CP value is required, the designated default value would be assigned unless the user chooses another value.

So why not add a column of radio-buttons to between the field value and the remove icon? Allowing just one value to be selected as the default.
Today if I want to have a default value added for all objects that don't have a value, I have to use a periodically run script to accomplish that.
Mike