For the original question... don't know & don't care since I'll never use Windows 8 beyond the several months I've already used it.
Why does it matter? You don't need more than 16GB.
And even then, let me know when they start reasonably using more than 2GB. And let me know what that application is.
There are dozens of uses for more than 16GB RAM, just because YOU don't use them, doesn't mean they don't exist for desktop use.
I'm sure they have a reason for this... the developers of Metro 2033 recommendations for optimum setup:
Processor: Core i7 CPU
Memory: 8GB RAM or higher
Graphics: NVIDIA DirectX 11 compliant graphics card (GeForce GTX 480 and 470)
DirectX®: DirectX 11
Surely, there's no reason that ANY game would need more than 2GB RAM... I mean, you said it yourself...
Try encoding 90 minutes of AVCHD 1080p 60fps 28Mbit/sec video to Blu-Ray on 2GB RAM, then bump it up to 8GB RAM, then 16GB, then 32GB, then 64GB
Try rendering a 1 minute 1080p animation with 3ds Max using the above method. This can take several days just for one render btw...
Forget the exotic stuff, how about batch processing vacation photos through Photoshop, like the 1200+ 7-9MB each JPEG photos I took on my cruise last year, batch processing as follows: auto level correction> auto resizing> auto renaming> auto saving on my photo drive in groups of 200 photos at a time. Should be a piece of cake with just 2GB RAM if you're right, go ahead & try it... then try opening 500 at once... then all at once... now try it with 4, 8, & 16GB RAM...
Sure this stuff is generally going to be done on a workstation built for that specific task, especially the 3ds Max rendering, but I can't afford such a workstation for my photo work / video editing/encoding/authoring, so it's done on my gaming rig / daily folder / email checking PC. I can tell you from personal experience, that even a 24 minute vacation video (originally shot in 30 frame progressive 35Mbit/sec 1280x720) encoded to Blu-Ray with Premier Pro CS5, goes several minutes faster on 16GB RAM than it does on 8GB RAM.
Please, stop applying your personal experience to everyone else, and/or stop thinking in terms of gaming only. There's MUCH MORE out there, I haven't even begun to scratch the surface...