I don't think every form has to contain all elements. I could see a form existing that specifically focuses on hand/arm movement linked to the upper body and rooting (or its equivalent). That could be done with little or no footwork, and certainly without the specific footwork you'd expect to use most often in fighting, especially if restricting the footwork makes it easier to see/feel the principles.You have just given examples why people don't fight as they train. Because the form may not contain the principles/strategies/techniques that people need to use in fighting.
If a form has no footwork training, how do you expect people to fight?