This x 1000.
OP there is no SP2 because Microsoft suck. If they had made a decent job of windows 8/8.1 to begin with there wouldn't be droves of people looking to stick with the older OS in the first place.
Microsoft has been "messing around" ever since Windows 6.0 (Vista). Not sure what OEMs were thinking putting only 512 mb of ram on Vista systems. They fixed a few things, resulting in Windows 6.1, gave it a new name, Windows 7. Anybody compared Vista SP2 to 7 SP1? They are very similar. The 7 got very useful Windows XP emulation, which was handy to have.
So we have Windows 6.2 (Windows 8), the file explorer got back the navigation arrow (one level up) that had been missing since Windows XP. Metro interface, no more Aero. No more classic GUI. Many other good things were added, though. Faster start-ups/shut-downs were among the most noticeable ones, display driver model saw another update (not as significant as the Vista-to-Windows 7 one though). They got rid of the Windows XP emulation mode (basically VM w/ key).
In 8.1 they decided to revive the Start menu button, just that. Still no useable Start menu panel. Killed the software emulation support for older CPUs like Operon 180/Athlon 64 X2 on the 64 bit OS edition. Basically leaving dual-socket Opteron users with heaps of ram, no choice but to "downgrade" to Win7 x64. Except for the security updates Windows 8 is a dead OS, you can't even install IE11 on it (which is ironic, because the older Win7 has it), AMD stopped making drivers for 8.0, etc. Security-wise, Windows 8.1 is the best Microsoft OS so far, but it lacks proper GUI, Windows has been known for. If you don't play games, you don't need Windows anymore. Period. *nix has grown into something, even a housewife can use it (compared to what it was 20 years ago). And it's free, no more stupid re-activation every time you change XYZ in your computer.
N.B. Windows XP is classy, the best Microsoft OS of all times with hardware sound acceleration, even though, it's no longer supported and is indeed slower in modern apps on modern hardware. With an SSD and Google Chrome, it's still usable, since not every old computer is upgradeable with the same functionality (S3 support is very patchy on newer OS's w/ older hardware with CPUs often lacking power-saving p-states as well)