Because the data is insanely useful. iOS uses it to show a map of your photos so you can browse by location. Google photos also lets you search by location. It

Because the data is insanely useful. iOS uses it to show a map of your photos so you can browse by location. Google photos also lets you search by location. It can also be used by image processing software to apply default settings when importing photos from cameras. You may have set up different profiles for different cameras based on what you have found looks best for the hardware. Almost all social media strips this data other than really amateur stuff or 4chan. Or in the case of vice, their own site.