Adam Smasher have plenty of story to tell. Unfortunately just not with V & Johnny Silverhand story apparently. His real story exist when MORGAN BLACKHAND APPEAR! In which a clear biggest missed opportunity that the main story told "as of now."
Morgan Blackhand is the real rival of Adam Smasher, not Johnny Silverhand. Bear in mind both of past memories missions are screwed perceptions/memories of Johnny Silverhand, not the "historical facts." That's why one of the final word reactions when Adam Smasher got beaten & V mentioned Johnny, he said "what the hell are you talking about?"
Adam Smasher Boss Fight is pretty much a power fantasy "fan service" imo. Realistically to the lore, in no way V or Johnny can ever beat the millions eddies borg like Adam Smasher. A one grab/shot from him is enough to kill V for sure.
From the overall V & Johnny perspectives in this game, I think Adam Smasher should have been the one that critically wounded Jackie to give player even more laser focused motivation on him, instead of the attacks from Arasaka drone & "fall damage" hehe
From the gameplay perspective, I think Adam Smasher boss fight should have been way way way waay more harder & deadlier for sure, especially on Very Hard difficulty LOL. Maybe something like:
+ have multiple armors & health bars
+ Immune to any negative effects including stuns/stagger
+ Immune to some quickhacks
+ have one deadliest attack that could almost kill player
+ have a multiple stages/transformations
+ Overall attacks are simply faster & deadlier.
Basically make the boss fight as hard as Sekiro or DMC5 or NioH or for FPS game like DOOM Eternal.
Also, I really think the game shouldn't even give choice for player to spare or execute him, making him unkillable in way. A scenario where the fight ends & V only managed to beat him in some way, a duel to survive, not even revenge. In any case, I think Adam Smasher is still alive (yes, for real). Even though if player executed him. Why??? He is ARASAKA BORG, I am sure that's enough to tell you that CDPR & even the actual lore could easilly bring him back to the story in number of ways.
As for the big villain talk. The real villain of this game is always been death itself & a philosophical fight between Corpos & Anti-corpos.