Parameter creation can be simplified, users should be able to type a Parameter name, an equal sign "=" and the parameter value to create a parameter, (e.g. "Length=500mm)". This should then pop-up a HUD where the category, units, instance/type properties are configured around the mouse cursur, so you do not need to leave the modeling environment to go to the ribbon for each and every parameter! Furthermore, you should be able to use math expressions using the parameter name or by clicking on a dimension to automatically fill-in the associated parameter name in the input box.
Example from Fusion 360: