We did exactly the same thing with Hugain without improving the midfield first
Pogba was already set to leave the club, it was only the matter of how much money the club would get from this transfer. At the same time, it was a year when Napoli came dangerously close to winning scudetto. Having bought Higuain, especially having bought him the way it was done, Juventus completely demoralized them. They still cannot recover after that situation, especially in terms of mentality. And, by the way, when he was bought, it wasn't Higuain we all know today - it was a ruthless goal scoring machine that just broke the all-time Italian record.
So, if back then the management already decided that their main objective was 10 scudetto in a row, they made the most effective move to simplify achievement of this goal.
