If you’re training for real life flight, then it stands to reason that a more realistic approach is superior to a less realistic approach that was only used because hardware couldn’t handle a more realistic approach at the time. I’m quite happy that hardware and software optimizations has evolved to the point where we don’t have to settle for those old workarounds anymore.
Because it’s volumetric. You can see the fog bank in the distance, fly into it, fly out of it and see it disappearing behind you. You can watch it dynamically move in from over the ocean or form in basins in the distance, so weather phenomenon like the Southern California marine layer or inland smog\fog bank (see screenshots) is pretty accurately depicted with MSFS, but not in FSX or any of the older sims.
Volumetric fog is far more precise than fog that extends to infinity with a circle of visibility that follows you around until it’s time to transition to the next global visibility that covers the entire world. I agree though that we need more control over it.
The atmosphere in MSFS is made up of a 3D grid that is rendered almost as far as you can see (within a reasonable altitude). Each cell\cube of that 3D grid within your line of sight plays a role in how the light is scattered and how the atmosphere is rendered overall. Every individual pixel of the sky is dynamically governed by the conditions of each atmosphere grid cell\cube within your line of sight, instead of the old system which was just a texture on a sphere. Since the atmosphere in older sims was not volumetric, your plane was the reference point and there was a single “visibility” value that extended out from your plane. Asobo correctly realized that that’s not how real life works and implemented a more realistic volumetric atmosphere system. To precisely control a volumetric atmosphere, you need to be able to set the conditions of the individual cells or use some sort of reference points because the conditions don’t follow you around. They’re actually tied to the world now, not your plane.