Juventus was clearly better throughout, and if anything final score flattered ATM. Surely you can't claim that the approach was right? Especially since any goal scored by ATM would make it infinitely harder for Juve.
Of course the approach was right. It was not the most pleasing to watch but it gave Atletico the best chance of getting a favorable result. You play to your strengths, and not help your opponent achieve theirs.
They played their usual 4-4-2, with (excluding injury and suspension) the same lineup that won 2-0 at home. In fact, the lineup in Turin was more attack minded with Lemar instead of Thomas and Arias instead of Filipe.
Atletico have never been an attacking force (even in the 1st leg, Juve had 64% possession), and with the 2-0 lead, their best shot is to defend well and take their chance on the counter and set pieces. With the team weakened defensively, trying to have a go at Juve would have only made it easier for Juve to score.
On the other side, you have juve who are playing at home, having played their last game also at home on Friday, rested all their key players and are overall a better team than Atletico (even in defense). Juve also have a player like CR for these kind of games. Most importantly, Allegri learnt from the first game and went for a more direct and aerial attack.
For perspective, two seasons ago, Juve beat Barcelona 3-0 in the first leg and in the return leg, they sat back and forced a 0-0 draw.