After we decided MAD probably wouldn't make the cut we discussed what you said, where you have one BAD and no helpless afterwards.
The problem is (as was MAD with a few other things) coding space, and priorities of codes.
Simply put, BAD is not broken anymore. We have created, as far as we can tell now, a much more offensive metagame, where approaches and baiting opponents have become more important than camping. Spamming ADs, which would work in vanilla, simply isn't effective anymore in Brawl+.
On the topic of off-stage, with grav mods and the increased importance of edgeguarding, BAD does not have a big effect anymore. They will most likely get one AD off if needed, then the edgeguarding player has to in turn react and continue and fight the guard break.
With air dodges saving people from dying, hitstun fixed that.