Not sure why you'd need a full on ATM machine?
You don't, but some people are going that route because of the familiarity aspect of the large ATM, as well as a ready made kiosk that can be readiliy secured in public.
If it's just a PDQ and a touchscreen monitor then it just needs to be vandal proof rather than secure. If it's within a shop, library or community centre then it doesn't even need to be that. The beauty of bitcoin is that the value of the bitcoin would not stored within the machine. If someone stole all the equipment then they'd just have the equipment and not the bitcoin.