The B4 was changed because it was AIDS. It was an inconsistent RNG cannon that either did nothing at all, or instantly killed a medium tank with lucky scatter.
I'm not saying that the "new" B4 is a good unit, it seems as though it needs further changes, but I am glad that the Balance Team seem to want to rework it into less of a memegun and into something that's actually usable/not AIDS to play against.
I'd personally suggest the AOE be increased on shells significantly, the damage somewhat lowered (So it doesn't obliterate squads), the number of shells increased, and perhaps having landed shells cause suppression/force buttoning/stun vehicles temporarily. I expect numbers would want to be tweaked a lot, but I think this would give it an identity apart from other howitzers. "Massive single nuke" certainly fit the B4 thematically, but I don't think it was something that could really stay as it was.
All howitzers are pretty AIDS to begin with, though.
The B-4 doesn't deserve to be reworked. Its an intentionally designed death cannon that largely had an impact in only team games, and hitting a tank with a direct hit was extremely rare to begin with. I have no justification for the existence of this gun, other than it's unique, memey purpose. Whats more, it needs the accurate shot back, but it does less damage to compensate and not insta kill tanks. Whatever the solution may be, it is not what the modders thought up of.
Might as well give it confetti instead, I'd rather have an useless artillery piece that MIGHT be completely busted, and not this three shot noob trap