These certainly are areas that deserve our attention, but these are far from the only mobility issues that we need to focus on within the home. There are dozens more that involve every joint, tendon, ligament, and muscle in the body.
Mobility is so much more than walking or stepping. Think of the way people use their hands in the home - to open doors, operate light switches, use faucets, open cabinets and drawers, use small appliances and grooming items (hair dryers, razors, combs and brushes, blenders, mixers, microwaves, and coffee makers, for example), get dressed (including putting on shoes), fix a meal and eat it, shower, use the remote control for the TV, open windows, adjust the thermostat, and so much more. Accounting for all of these movements that someone does during the course of a typical day means that we need to be aware of all of the challenges that are present for people to grasp, hold, use, place, turn, and otherwise manage the various functions that are hand-operated or controlled.
Another aspect of mobility that involves the hands, as well as the arms, shoulders, elbows, and wrists, and sometimes the back and legs, is reach items in cupboards, drawers, refrigerators, closet shelves, and other places in the home where reach, range of motion, and hand and arm strength come into play. People with limited range of motion (how far they can rotate their shoulder or elbow, for instance, to reach for something or attempt to hold onto it), a weaker ability to hold onto items once they have touched them, or being able to retrieve something from a shelf without dropping it, may find that cabinets are mounted too high from the floor to reach easily and safely, that cabinets and closet shelves are too deep to retrieve items from the back, that closet rods are too high to reach without stretching, that range hoods cannot be operated without assistance, and that other storage areas and appliance present issues for them.
Consider sitting and standing - at the table to eat, in the living room or den to read the paper or watch TV, and in the bathroom to use the toilet or take a bath. How easy it is to get to where the sitting needs to occur and the height of other objects (such as a counter or table) factor into how functional the act of sitting and standing might be. In standing, do people require any type of assistance such a grab bar or support?
The location of other items in the home needs to be done with mobility concerns in mind - normal mobility and more restricted mobility from arthritis, a stroke, accident, fracture, progressive condition, or deteriorating joints (knee, hip, shoulder, or spine, for instance) - to accommodate using the various areas of the home effectively. The kitchen and the bath will require more focus and emphasis because of the amount of physical activity that is required to use these spaces for the activities that typically are done in these rooms.
It's not hard to accommodate a range of mobility concerns - and universal design and visitability strategies will definitely help - but we need to take a comprehensive view of just what is involved in someone being able to use their home successfully without encountering any serious mobility challenges.