You could probably do this yourself fairly easily on a a per area basis. You fire up the scenery editor in the developer mode and draw a big vegetation exclusion rectangle over the photogrammetry area.
I agree with you on this at times. The autogen trees can look great by themselves in remote areas, but they are grossly oversized, which was intentionally done to hide the photogrammetry trees and also improve performance by using less tree assets. So many residential/low-rise photogrammetry areas are now completely hidden by overgrowth though. Not to mention all of the approaches that have been destroyed by trees. The latter is going to be fixed by the World Hub fairly soon I hope.