The reason that Macbook Airs as well as iPhones use these screws is to protect someone that is incapable of repairing electronics from trying to. If you were to do any research on the battery technology in both the iPhone 4 and Air you would quickly notice that they use soft lithium ion batteries with no shell. This means they could potentially vent/catch fire and seriously injure whoever is working on them. Apple has a requirement that stores have specific safety equipment to deal with these types of fires should they occur during a repair. If a tech needs a firesafe, special powders, gloves, tongs, masks, and other misc tools to safely repair these products would you really want to chance a home user dissecting this on their desk?