When you include the fonts as part of the Package command (File>Package), InDesign now generates a Document Fonts folder. When you open an InDesign file that’s located in a folder that also includes a Document Fonts folder, InDesign will automatically install the fonts the document needs! And when you close the document, the document fonts are automatically uninstalled for you. So is there ever a reason not to enable the Copy Fonts checkbox in the Create Package Folder dialog? Uh, no.