imho, desktops don't hold an advantage over laptops. I've been desktop free for years, and my MacBook pro kills it when it comes to graphic design, photography, video editing, gaming, general productivity, etc.
Now, I agree tablets do have a ways to go, and are not quite the desktop/laptop replacements Apple and Google want them to be. With that said, most people don't know how to optimize their tablets.
If you look at the "Industrial" Photos under my photo stream, all of those were directly upload to my iPad from my DSLR and edited there as well. I can easily create and edit MS Office docs as well as iWork docs, edit video, manage twitter, G+ and FB, manage content and ideas in Evernote, and even program.
Yes, program, as long as you have an internet connection so you can compile your code.
So, tablets are making more headway than people know.