Many of Italy's great art treasures are owned and managed by the government

The standard economic case for government support of the arts contends that it corrects a beneficial externality. The arts, while directly enriching artists, art firms, and art consumers, also produce benefits that accrue to the rest of us in terms of education, prestige, and expressive freedom. People benefit from living in culturally enriched communities, and the communities receive prestige by the presence of artistic centers.

Thus the answer to this question depends on your feelings about the importance of these externalities, which are difficult to measure monetarily. Taxes will be higher when the government finances the arts, and some will not value them accordingly. Apparently in Italy, the feeling amongst the voters was that they didn't want to pay for keeping these works in public ownership. With so many cultural artifacts, it is understandable that the government of Italy would be hard pressed to preserve them all in the most careful manner.

When works of art are owned privately, there is concern that they will be removed from the general public for viewing. This is certainly a concern. But, practically speaking, private curators have proven very diligent in preservation, and their collections have formed the basis from which many museums have been founded. Governments and public museum face lean times from time to time, making it difficult to maintain them from generation to generation. Many of the externalities mentioned above will still be present if the private curator chooses to display the works of art.