I was one of those in his last season who wanted him to go because it wasnt working anymore. He was part of the problem, but not the main problem.
His stubborness also cost him the job because he was going with the same team and formation despite it not working. For example Montolivo as the anchor 12/13 was a major success, why did he change his role completely to a box 2 box midfielder the season after and gave de jong the anchor position? I don't get how you could change a winning team. And also limit one of our best players (its quite clear that its important for the team that one of its best players performs). This was also not the only change he did, but several others. And despite the results going shit, he continued with the same players. He could also have changed to 4-2-3-1 formation but no he continued with 4-3-3. He was incapable of a change cause he was too stubborn.
But, all in all, even the most allegri haters can't get away from this fact, is that he did more than a good job with Milan winning the title the first year. Second year 2nd place, but we really should have won the scudetto this year too, and the 3rd year we got the CL qualification place despite selling Ibra and Thiago and being called out as a mid table team during and before the season. His Champions League adventure was a bit disappointing though, being eliminated by babies at this stage by tottenham and poor results in relatively easy groups. We came second in the groups all three years and because of this you obviously meet tougher teams in the next stage.
I think allegri always has been an intelligent coach, and he is showing it in Juventus now just like he did with milan in his first years, its just that he made some wrong and crucial mistakes in his last years that was end of an era. But you cant only blame him for the horrific season, the managment did very little to satisfy allegris needs.
Juventus completely dominates its opponents from the start to finish now with allegri, with much possesion. Conte was more the waiting guy. I think he can develop this Juventus and take it to the next level wich Conte felt he couldn't do and left. Also he has a managment who supports him 100% and listents to his needs, like not selling players he dont want to sell, buy players he wants etc. In Milan it wasnt like that.
But I don't regret allegri leaving. Im glad we have pippo now and can start something new and fresh!
cheers