It is not the super competitive league it was in the 90s but scoring in Italy is always difficult. Most teams when playing Juventus park the bus, and they know how to do it properly. Take a look at the last 30 minutes of Valencia vs Juve. When Juventus decided to just defend the spaniards had no idea how to break through, because they are not used to it.
Now that Ronaldo is here, this is even more accentuated, teams take pride in not being scored by him. Hopefully as the season goes on, the novelty effect will fade and we will be able to see some decent football.