I would say that unless a prohibitive policy suggests otherwise, two instances come to mind where I think adding such photos is of value:
# Is it unique? Or is it essentially the same photo that's on e.g., Wikipedia, or Find A Grave, already?
# Is it a direct descendent? I think a "personal reflection" note about the artifact (even if it wasn't done contemporaneously - statues, for example, that are still around must be considered of some sort of artistic, heritage, or other historic value or they would not have been preserved), and how you feel it honors (or doesn't) the ancestor.
Either of these instances are worth strong consideration for inclusion, because the profiles we build are an extension of ourselves; so even the discovery expedition, or a purposeful one, is worth of documenting.