Obviously it's entertaining as hell to watch them lose their sanity and become deranged, or possibly turn into a maniac or "the Unashamed".

But once you've done that enough times and the novelty factor has worn off, is it really all that useful? On rare occasions I'll do it with a legendary captain if I think they look cool or have OP abilities and are too high level for me to dominate. But typically it's not all that difficult to find ones that are at or below your level, and you can kill the high level ones for gear to either use or farm for currency. So is there any real benefit to doing it other than when you happen to run into a legendary that you feel like you NEED to have?