Your execution really makes me jealous with that GBoD... Gotta remember you use an Arcade stick... and that I have that I could be learning too. Also, best remix of Rock with you I've ever heard. What's it called?
I think the fun of the move is learning how to trap people into blocking. It does 6 more damage than the SPoD. Once started, it is all guaranteed if you can finish it.
I can do it fairly consistently, and I don't play Akira. I also can't see it being that difficult to set up, granted you do technically have to convince the opponent to block. Oh, and his hit throw is just P+K in this (to start it, that is). I guess my gripe is just that no other character has such an amazing "guard-break," difficulty aside. Difficulty loses partial relevance one a player masters it, IMO.
Considering it's execution difficulty, it doesn't do that much damage. His hit throw off of G+P+K (not sure on the DOA5 input) does more damage, is way easier to pull off, and can give you counter and high-counter damage when you can't with the GBoD.
Because the move is as awesome as it is iconic. That and it's hard as crap to execute consistently and you have to work for the setups to actually make it viable against a human player :U