I guess I shouldn't lock my car, either, right? After all, someone could simply break my windows and steal whatever I have inside. Or maybe, just maybe, using some protection actually is better than using no protection, provided you don't put more faith in the protection than the protection warrants. Just like I wouldn't store gold bars in my car, I wouldn't use jscrypto to protect things that were too important for that level of protection. I will, however, feel okay about keeping my sunglasses in my car, and I will feel okay about using jscrypto to send my phone number over email.