In an interview with Zatan last night he said Inzaghi makes him more free on the pitch.
That's because in a 4-3-3 with Dinho and Pato wide, the two CBs are always on Zlatan's back. Inzaghi's movement in and near the box keeps at least one of the CBs busy all the time and there is more space for Zlatan.
Milan have 4 quality strikers + Ronaldinho. As strong as it looks, I think they'd do better if they had a solid midfield, with Zlatan as a SS and Pato as CF.
Good thing that Berlusca thinks only about marketing his team and he will buy 100 star forwards if needed, but he won't intervene in midfield and defense.
I don't understand why Milan keep playing Pato wide.
Berlusconi will play all 4 of Robinho, Pato, Zlatan, Dinho if needed, but that will be too foolish so he most probably made it clear to Allegri that starting at least 3 of them is a must. Granted, Allegri has the 4-3-1-2 option but my guess is that Dinho doesn't want to play centrally or that they tried it and the lack of width was a huge problem, so 4-3-3 was the only possibility left.