Mourinho managerial philosophy does not fit Arsenal style of play, Arsenal plays attacking and possessive style of football which is more entertaining however mourinho 'packing the bus' tactics or defensive style of football is outdated and Arsenal fans wouldn't subscribe to it, I prefers any attacking minded manager to be appointed thus continue with club philosophy and of holding, passing and attacking with the ball.
Mourinho style is similar to Simeone and Conte but he is different than two coaches. He complains and attacks his players so much that Conte or Simeone don't do.
The team lacks all the players needed to get Arsenal to top 4. Arsenal fans probably missed Arsene Wenger now because back then some fans wanted him to be replaced because he couldnt get Arsenal to win anything higher then the 4th spot
The cycle in football is about ten years. The gold period often last about 3 years. By that I meant if a club reach their golden time it will last up to 3 years and then they will have to rebuild their team. The rebuild process will take about 5 years and they will reach their next golden time 2 or 3 years later.
Golden time for each club does not mean they will dominate their national league or Champions League but at least it is time they have highest performance for each generation of players.