The artifacts belonged to India not to the United States. We returned them to their rightful owner. India does not have a history of abusing their artifacts or being careless with their history. If it were a country in the middle of turmoil, perhaps the argument could have been made to not return them.
I think every country has the right to ensure the preservation of its culture and heritage. It can be considered as an extension of its sovereignty. Even if it affects commercial interests of its people or of other nations, it needs to be upheld. Heritage is part of the traditional knowledge of the respective population. They are not to be deprived of such a basic right for the sake of glory/ego of certain organizations or individuals.
Returning the artifacts was the right thing to do. They were acquired by theft, so they were not the rightful property of the United States. I applaud the U.S. government for giving them back to their rightful owner. Not only is this the fair thing to do, but it also could help build trust and goodwill between the two countries.
No, the US should not have kept these artifacts, and they did the right thing in returning them to the country from which they originate. It is important for artifacts to remain at their sites, especially if they are from cultural heritage sites. They are important for the tourism of their countries of origin, and the US should expect the same treatment should another country find that it has important US artifacts.