Suddenly, they all seem to have the technology to build ultrabooks, a year prior, one one had any technology that could even remotely come close?
The same goes for so many aspects....battery life, screen resolution, looks....Apple blows almost every single other company out of the water on almost every important aspect, except perhaps price, and even there you can even make the argument that they are better.
So yes, it is hard, but it didn't just suddenly become not hard in the last year where some OEM's are finally starting to come out with attractive products. And despite how hard it is, Apple somehow solves almost everything - the only thing OEM's seem to take an interest in solving is either hitting a very low price point (and they'll cut every corner it takes to get there) or the extreme upper end of performance.