Though a physical case for a personal computer is much larger than than a touchpad, so much can be held inside the case. With the touchpad all the extra wires to make the system more bulky. On the other hand with the desktop you can access anything the touchpad can via a network.
Why I am less likely to get new equipment? On both the desktop and the touch pads, you are not free to install what software or hardware you want. It is the vendor's way or the highway. You do not treat customers that way, Apple, Android, and the rest of spoiled brats maybe off the market with all the new open platforms coming.
With open source you are more likely to get software upgrades for a longer time. We still use early Pentium based desktops for various reasons . For example the Nexus 7 will still get software fixes and et cetera, but no more upgrades coming. When did longevity go out the window? It's your choice.