As you tighten a bolt the angle you need to apply force changes. So it’s not just a fixed position plus force in 6 directions its force in 6 directions at each position. You can learn quite a bit about something from such interactions such as an objects weight, center of mass, etc.
Further robots generally have more than a single rigid manipulator.
Yes, it's time-varying data, but there are not that many channels. And the sensors are off the shelf items, although overpriced.