I agree that multi-plant images would sometimes fit the category I had in mind. The specific plant would not have to be the main focus of the photo, but the photo would need to provide a real feel for the character of the plant, how it looks in use. The photo couldn't be just a mass of foliage and color, part of which would just happen to be the plant in question, even though that would qualify for multi-plant.
On the other hand, there wouldn't need to be more than one plant in the photo. It could be by itself in a pot, or planted under a window, etc. The idea is more to get a sense of what the plant looks like from ten feet away, rather than right in your face.
This is a type photo I always want to find when I am researching any plant with which I am not familiar. For me it helps fill a need met when I see the plant in person. I don't just mean the ATP database. So many times I have wasted a lot of time trolling the internet trying to find a good perspective photo of a particular plant. Everyone wants to take closeups of the blooms if that is the attraction, Or of the foliage if it is a foliage plant. Or fill the frame with the entire plant so you can see the details. I'm a details kind of guy, so I get that. But I also want to put the plant into perspective.
However, I concede the point. The category would need to fill a need for a much wider audience than just me. It would need to fill a need for the general "viewership" of the site, and clearly that is not the case.
Thanks everyone for considering the idea. It's nice just being heard.