A99 has it (albiet horribly named and difficult to find). We know it's possible. There is no excuse, Nikon. Make the D800/e usable by studio shooters. Right now. Firmware update.
Edited to add : Whether Aperture is respected in LV mode should be a separate option. Many will turn both off for optimal LV illumination/quality, but there are a number of reasons (not least of which is focus shift) one might want to focus at shooting aperture.
Page 46 of the D800 English manual says of Exposure Preview...
"During live view photography, you can press OK to preview the effects of shutter speed, aperture, and ISO sensitivity on the exposure."
Do you have some sort of mental affliction that uncontrollably compels you to press the OK button? ‘Cause it seems to me that all you need to turn off exposure preview is to never turn it on.
That doesn't apply to manual exposure mode, which is the mode one uses with studio strobes. In that mode exposure is always simulated. If you're shooting with strobes in a studio with dim ambient light your live view is black (or so nearly so as to make it useless). It can't be turned off.
If I have some mental affliction, Thom Hogan has it too as his review confirms this.
Okay I understand now (though Thom Hogan may still have a mental affliction...but that's a whole different story altogether!)
I never use Live View myself, but I agree that it doesn't makes sense to have M mode work differently...and also not say anything about it in the manual. I wonder if it's just a bug in the firmware. Have you asked Nikon about it?