Biel is of the same mind as I when it comes to ambient occlusion, and though I would like to discuss that further, its not really meant for this thread. As for foliage, bright outdoor areas in idtech4 usually use a lot of non shadow casting, or ambient light to simulate indirect lighting. In these cases, its hard to argue against the use of ao.
Back to my question. IF one could light an outdoor area with few little non shadowcasting light ( putting aside how lousy it may look for the sake of arguement ), and also have alpha surfaces cast shadows, would ao specifically for foliage still be that much of a nescessity?