The rebuilding of the Temple is a momentous thing for Israel because it means a return to normalcy in their relationship with God. Remember- exile came because they were not in right relationship with God. The rebuilding of the Temple was the ultimate statement that the relationship was restored, and they could return to worship as they knew.
Yet, the celebration was mixed with tears. As some cheered for what they were getting others mourned what they had lost. As some were going to experience the Temple the first-time others were being reminded that the Temple was not the same as they had served in before. There were certainly mixed emotions. You could not distinguish joyful shouting from the sounds of weeping. I think this type of thing happens when churches change buildings. There are so many good memories in the old building that it is hard to say goodbye. At the same time there is excitement for the new opportunities in the new building.
I think that we sometimes forget we can have mixed emotions. We can be happy for the future and nostalgic about the past at the same time. We can look forward to what is next while mourning the loss of what has been. We have emotions like this throughout life. Like when a kid grows up and graduates from school. We are excited for their futures and look forward to their next steps in life. At the same time, we miss the little kid and the times we had with them in our house as they were growing up.