I agree with you, Adam.
If the picture makes you go, "wow" then it's a good image irrespective of how it was done, where it was taken or what's in the image. The image has to tap-in to some form of emotion for it work. It might make you smile, it may make you thoughtful, or sad. But "wow" is top of the list.
I find the same as you with macro images: hard to sell. Woman (preferably) diver on colourful reef; or dolphins sell. Incredible shots which took 73 hours without moving at 69m up the nose of the extremely rare minidinkus tinybuggeratus just does't float the boat of too many picture buyers.