Photoshop Save As DNG please

Save as DNG from Photoshop (not from ACR, that is already possible) would be useless, as explained 5 months ago. It would be a flattened TIFF in a DNG wrapper. 

BTW, saving a focus stack made from raw files as DNG would be another matter. That would/could become a DNG like the panorama and HDR DNG files that Lightroom and ACR can produce. That kind of 'Focus Stack DNG' is already possible with HeliconFocus.

I am very curious what such a feature would do for you.

Save 1-2 GB of storage per image, roughly a 90-95% reduction. Before conversion to DNG's each TB could only store 300-600 images. I'm only stacking 5-10 shots. If someone is focus stacking 100's of shots for macro photography, they can easily end up with 25-100 GB per image.

How exactly would you save that much? DNG does not support layers, so if you compare saving as a 'flattened' DNG with saving an uncompressed layered tiff, then I see where the difference comes from but that is comparing apples and oranges. I don't see why a flattened tiff saved with zip compression would be significantly larger than the same image in a DNG wrapper.

You are comparing apples and oranges and you don't understand what the DNG format supports and does not support. That 25-100 GB per image is the layered image. If you would flatten it and save it as TIFF with ZIP compression, then that would give you 90-95% reduction too. DNG does not support layers, so if you would save it as DNG you would also flatten it.

You are comparing apples and oranges because you apparently do not know what the DNG format supports and does not support. You seem to think that DNG is some kind of miracle file format, that can save huge files with extremely high compression without any loss. If that were true, I would obviously support your request! Unfortunately that is not true however, there is no free lunch. That 25-100 GB per image is the layered image. If you would flatten it and save it as TIFF with ZIP compression, then that would give you 90-95% reduction too. DNG does not support layers, so if you could save it as DNG you would also flatten it. And the flattening is what reduces the file size so much.