NEB was developed to fill in a niche market, those countries who have MK82 GPS/LASER guidance kits can use NEB without any modifications or adaptations.
BLU-109 requires GPS/LASER kits that is especially adapted to BLU-109 shape, form and flight characteristics.
Also, NEB was never meant to exist, it is the afterthought or maximization effort of the R&D that went in to development of the warhead, which came to fruition because SOM cruise missile required a light weight yet effective bunker busting capabilities, so the warhead was developed for SOM and adapted to fit inside a MK-82 shell.
If you want to know more about the capabilities of NEB, research BROACH warhead.
