To get one man army you have to not take any talent point apart from what you start with.
You do bring up a fair point, and a "One Man Army" game mode sounds like it might be interesting (player is buffed a lot, but cannot recruit companions). Larian probably would not like having to support a new mode which is highly imbalanced, though.
You did forget that One Man Army requires you to be level 8 and you literally cannot take it at character creation. You later seemed to remember that, which makes your argument confusing.
In any case, clearly we should not be able to take One Man Army on all four characters and keep them in the same party. That would make it so powerful as to be a "Must Have" Talent.
Vitality isn't terribly interesting at the moment - either you are dead or not. You are better off spending on armour than vitality.
What are you talking about? In this build, the Defensive abilities no longer include Vitality, Physical Armor or Magical armor.
If you mean from attributes, then it still doesn't make sense since you're only getting 1-2 percent of armor per point into STR/INT, which is zilch below 100 armor, and effectively zilch even above 100 armor. If you're looking for improved survivability, CON at least makes the numbers visibly move.
