Endnote should support API access to external programs and possibly plugins.
There are niche ways that interacting with the endnote database, and having those interactions be represented in endnote, would make sense. For example, I am conducting a lit review. I happen to be using endnote for significant parts of the process, but it is very clunky and too limited. Yet it serves as a useful tool for coordinating and recording parts of the process. It would be more efficient if we could use our own custom lit review software, but have it actively working against endnote's database, using endnote's groups and citation information, perhaps even forcing syncing from outside the endnote program.