If we're talking about the desktop being perfected....eeehhhhhh. Not so much. A generic black ATX box with entry level peripherals doesn't strike me as perfected. Usually if someone is in the market for a desktop, they're probably building one themselves or it's for the enterprise space.
If we're talking about laptops....eeeehhhhh. maybe. It's not as great, but it's pretty much stabilized spec wise and with several different price points.
If we're talking about tablet PCs, that hasn't even come CLOSE to being perfected, holy crap! OEMs are still using the ipad as a design template over actually thinking otherwise. More I/O connectivity should be in place for tablets, basically build them as a laptop. Build a tablet that can be user serviced. Build a tablet that is simple for simple use for people with simple needs. Build a tablet with higher end needs for people who need more higher end portable needs. So on and so forth. The laptop form factor has that type of thing with different specs for different needs. Tablet PCs aren't even there yet.
But if we want to put blame, I'd actually put some blame on Windows altogether, mostly vista. Since vista, OEMs had to raise their specs on their PCs from a single core processor and 2 gigs of RAM with small hard drives to dual core and 4 gigs of RAM standard with very ample hard drive space. The year of 2008 was about when this came about as the industry standard as the Windows OS at the time was horrid without higher end hardware. Then came 7, which made running the OS on that new standard of specs even smoother, 8 even more. Microsoft has dedicated themselves to making sure future Windows version are even more streamlined, primarily due to the use of MinWin. There isn't a need to upgrade those specs anymore. vista needed a proper graphics to just run Aero, same as 7 to a lesser extent. In Windows 8, a graphics card that was slammed trying to just run vista or 7 in Basic mode runs pretty ok with Windows 8. Even on an xp era PC, Windows 8 can run better than on that PC than xp could.
And there lies the snub, OEMs built PCs at a higher standard of hardware to run an over the top superfluous UI; which if ran on Windows 8 runs very smoothly. This is kind of where Windows RT also comes in, the ARM processor for a lot of people is actually just fine, look at the ipad and android tablet sales. People have those tablets in conjunction with a PC because of a lack of certain PC software on the Desktop. Theoretically and hypothetically, if certain Desktop apps were to be compiled in the WinRT form (meaning the ACTUAL entirety of the Desktop app is in WinRT form with the full feature set as the Desktop counterpart) on the ARM processor, Windows RT can really excel. Battery life is all day on those tablets, performance is actual quite decent. Thus in turn means tablet PCs are thinner, lighter, and less expensive. What will happen is that Windows RT could be used primarily in the consumer space, x86 processors could be used in the enterprise/enthusiast/workstation/gaming PC space.