I think that as the developers are developing them on better hardware they pay less attention to performance. For example you wouldn't expect the lastest build of iTunes, or OS X to run on hardware for 10 years ago. As system specs improve developers seem to pay less attention to performance & file size. It seems crazy to me that modern web browsers are over 50mb in size. But as hard drive size isn't really a constraint anymore the developers don't optimize that aspect as much.