Expanded ISO

Often wondered why expanded Sensitivity/ISO isn't the standard camera setting. I have set my K5ii to expanded ISO as I like the low ISO 80 for when the light is very good and using slow shutter speeds. I haven't seen any draw back to having the extra High and Low ISO available so;
Is there a disadvantage and if not why not keep it set to Expanded Sensitivity then its there when and if you need it.

Some settings such as Highlight and Shadow correction are not available when in expanded ISO.
I assume this is something to do with the reason it is not default.

Down to 160 instead of 200 is available with expanded and highlight and shadow correction on. It is correct 80 is only available if Highlight & Shadow correction are turned off. i guess this is to allow a full stop latitude for these tools.

There has been much debate over time about getting the full dynamic range at which low setting. Actual tests here link

Personally i find with my K5 ISO 200 gives a superb real world range unlike many compact cameras. I use low for shadow correction. I guess none of this applies to RAW images.

I guess with the native iso for a cropped sensor camera to be around 200. This is wht you are getting results that are easier on the eye. As you are not working the sensor so much.

I have always believed the limit to ISO by default to simply be a way of preventing unintended use of extreme settings, either very high that would cause poor quality, or very low that might cause too slow a shutter speed. Its just to prevent unintended use by someone not understanding the effect of other settings they may be making. Obviously, should a user specifically need the extreme settings, then they have made that active choice.

Thanks for all the information, I now realise that the expanded sensitivity comes with restrictions to many other settings.
Regards David