Mantis keepers should be able to relate to the dramatic aspects of the hunt and capture behaviors that centipede keepers enjoy. For some the adrenaline rush of keeping something that could bite and hurt them too is part of the thrill! Think "skydiving" and "bungee jumping", or like I've been doing lately...risking your life to teach your 15 year old how to drive. Believe me, I feel much safer in my bugroom full of centipedes and millipedes!
One thing that seems to have gone unmentioned in this conversation about millipedes is their very gentle nature and communal aspects. In a beautiful, planted terrarium they amble about adding so much interest to an already attractive enclosure. And unlike most mantises, they can safely be kept in colonies together with even different species living together to create a really interesting communal display. Additionally, they are extremely easy to keep. A properly set up tank can be left alone for months at a time. No worries about feeding, or constant tweaking of humidity levels, or of molts.
Here is one of the many videos I've shot of millipedes. Even if you don't want to watch the video, press play and close your eyes. Let the music take you away from any negative feelings you may reluctantly harbor for any animal that has evolved completely independently of human approval (and consider and remember that many people in mainstream society feel the same way about our mantises!). If you can love one thing, you can love almost anything. I love millipedes and centipedes! I'm headed down to Arizona next week and hope I find another 8 inch Scolopendra heros!