...the new ministry believes it will decrease illegal immigration
For Italy it might be a good idea, since they have lots of immigrants from allover Europe
it creates big queues at customs, not comfortable
I believe Italy decided to resume checks because of big counterfeit consignments had been passing through its border and, thereby, gave a good hit to Italy's economy.
Or.. because many citizens from eastern Europe countries succeeded to obtain the citizenship of the eu members that were admitted recently.