I think that even though Diogo Simone has achieved lot with this club winning the laliga title and playing in the finals of the champions League some years ago he has ran out of ideas and has over stayed his welcome the best thing is for him to move to another club because at it's stand now ATM is now a club that has no ambition both in Europe and in the domestic league
I think Simeone is comfortable at Atletico, and the decision to change the coach should be made by the management. And I also think that everyone understands that it is very difficult to compete in La Liga with such giants as Real and Barcelona, and as you correctly said, Simeone managed to win the League and this is appreciated. Perhaps the management should be more decisive if they have enough ambition to fight for higher goals, but apparently they are also satisfied with the current order of things in the team. Simeone leads Atletico to the Champions League and reaches the playoffs, this is also a good achievement.