It would be nice to be able to create parameters without specifically opening the tool.
Example: While creating a rectangle in a sketch, you decide that you want to create a named parameter, and then assign it to the rectangle. Rather than opening the "Change parameters" tool, you could simply input into the box "myRectangleDim=.1in" and then the rectangle would be dimensioned with the parameter "myRectangleDim" and a parameter named "myRectangleDim" would be created with value of .1in.