I'm sure you can come up with others as well. Just be creative. This is hardly going to do anything for strength and flexibility, and it will only be a very weak cardio workout, but its discreet, can be done while working, and nobody will notice. Do it enough so that you can do various moves throughout the work day without paying much attention to it (and thus not affecting your work much), and you'll be feeling great without being "that sweaty, awkward push-up guy"
Only if it improved battery life by 10x...
That would only be possible if it is done in the cloud.
It is one thing to not "help" the consumer in replacing components by not designing for that. But once you start designing your device to intentionally make it more difficult to repair and modify, it is a whole different game.