Heya,
There’s a few reasons. The primary one being that the plugin expanded on the EXIF that WP was already importing. WP imported the basics: shutter, ISO, aperture, etc. Then I added geo out of my own desire to display it, and then a couple of other fields as people have requested.
I don’t think I’d want to import the whole EXIF spec in for every image by default as that would take up a lot of database space and would not necessarily benefit a majority of users. However, one could probably create an addon to import extra fields, and I take requests under consideration too.
One question to ask yourself is what’s the purpose of the EXIF you’re displaying. basic things like shutter, ISO, flash, and aperture help to inform and teach other photographers who are interested in any particular effects you achieved. If you’re teaching beginners-intermediates they are probably going to use automatic metering, but if you’re teaching intermediate-advanced users they may be interested in manual metering. White balance might be interesting if you are in the habit of white balancing manually a lot, but if you use Lightroom, or auto white balance it probably wouldn’t be instructive… I could be wrong.
So in summary, happy to take requests with good reason, but will most likely never import every possible EXIF field.
