The WSJ – and prevailing wisdom – blames two factors for the decline of PCs: PCs have become “good enough,” lengthening the replacement cycle, and more and more time is being spent on tablets and other appliance-like devices.
However, I don’t think these factors are independent; it’s not just that tablets occupy more of a user’s time, but that by doing so they make any performance issues on one’s PC less pressing simply because you use it less. To put it another way, users are likely to have a higher standard for their primary computing device than they are a secondary one; as PCs become secondary devices for more and more people the standard for “good enough” becomes lower and lower.
Ben Thompson has been on a kick as of late talking about his Chromebook, but I believe he hits the nail on the head with the title of the article. However I have to disagree with his statements above. I don't believe it's that PC's are good enough because they are now secondary devices, I believe most people were using their computers to do things that are better served in the tablet form-factor.
People have been using computers to do email, browse the web, go to Facebook. Most people who owned computers were not using them up to their full capabilities and didn't need all the complexity that is inherent in a PC Operating System, Mac or Windows. Most people just want to be able to do a few things on a computer and it has to be very easy. While I am very computer literate, I love my iPad because it is totally simple. I enjoy the simplicity because I just don't have the time to tinker. So the iPad model solves problems for all levels of users.
The downturn in the PC industry is simply because a technology (product) came out that made it easier to do what users wanted to do. If the iPad was more complex (like Android or a Chromebook), we would not have seen this downturn in PC sales.