The problem is that such fields will apply to the whole observation, not just the individual photos. There is a feature request to allow annotation/markings on individual photos, such that comments (like “ventral view”, “good diagnostic view”, “male/female in copula” etc) and even drawing directly on photos (such as circling which organism in the photo is the subject) can be done.
But by far the biggest problem, is that someone has to go through and apply all the “lateral”, “ventral” etc… and that effort probably makes just skimming through “all observations of taxa” looking for good comparisons far easier in the long run!
I have a bookmark folder, in which I try to have a bookmarked observation for all the main spiders I have difficulty with, and for those I make the descriptions match the view type that I have saved, to make them easier to find. But I rarely use it… I just browse the taxa observations looking for the right views to compare with, which are often composite (eg oblique anterior-dorsal for comparing an eyefield)
The number of observations (and growth) actually helps, as it raises the sample pool and increases the chances of finding a useful one by quick scanning the observations page. It also means you don’t need to look INTO the observations to see 2nd photo etc, as it is quicker just to bring up an extra page worth of obs to check next batch of 1st photos. Only if you get to the end and still haven’t found the good comparison do you actually need to go back and check 2nd photos etc.