I guess it won’t be any surprise that I have a lot of metadata entered in my Aperture photo library. In fact the lack of metadata support in Photos is the reason I can’t migrate there.
The real value of metadata is to help find photos, but sometimes the right piece of metadata is beyond value. For some paperwork related to my current husband’s ‘green card’ I needed the date of birth of my former wife. I could not remember it, but looking in my photo library, I found one taken on her 23rd birthday.
Of course I have the original date set on my photos, even those that I scanned from prints or slides. Because I had added the metadata when I knew it, I now had the all-important date I needed, and was able to file the paperwork.
Never underestimate the value of metadata!