We're not a 'top club' yet (I'm strictly speaking about the team in general, not the club itself), that's why. They have way better weapons in midfield and way more quality in attack so it's pointless to compare situations. I think we need to play the formation that suits best our team, not the ones that works good for others.
The formation 4-4-2 pretty much failed last season because we didn't have good wingers and we weren't all that in centre midfield either. Also, the squad changed so what applied before is not related to what applies now: we have a better sets of forwards, and to be frank we have Pirlo. When he has space to do what he wants, he makes us much better as a team.