Juventus finished the round of matches before the world cup very well, i feel they had to show something after being eliminated from the champions league, their manager's job was in danger, the players had to react and they did, their impressive performance took them as high as third position, and back in the competition for the title. The only problem is that Napoli have been too good, they still have a 10 point advantage on Juventus, and i do not see what will affect Napoli's form after the world cup, they would remain strong and will surely win the league with a big gap.
It's also true that Juventus had a lot of injuries and that they were practically playing in an emergency. Not to mention that he had no money to spend on buying or changing coaches (to make the fans happy). The calm and patience in keeping Allegri (who is a good coach) finally paid off once the injured players returned.
An Inter mentality, which changes coaches as soon as the wind blows a little,
leads nowhere.
I would guess that it wouldn't make sense to fire Allegri because there were no coaches that they could afford. Even if we stopped looking at the ones that are free agent (the other ones would have to be bought out basically) would mean maybe Tuchel was free to be hired, and I am sure between paying Allegri to leave and hiring Tuchel to come, that would have been easily 10 million gone very quickly, and they couldn't afford that.
So, it wasn't really a voluntary decision but more about the financial situation they are in. If they didn't have to fire Allegri and he freely left, they would be gladly getting someone better but that wasn't an option.