We have a board to evaluate new features and ideas and other board to develop them. Our labels identify the product or products related to that new feature, nevertheless labels are deleted by Trello when we move an idea to the development board.
Now relabel a moved card can only be done in the destination board. It would be more convenient for us to select the new label in the moving process itself (when we select the destination board) to ensure that important categories are not being lost in the process. Also Trello could suggest to apply the same color-label used in the previous board.