If I create a rigid body object, the geometry is automatically connected to an dop import node. I'm not sure what this node is good for.

I use a rbd object to select my object sop. No need for an dop import node. Maybe anyone can explain why this node is used in all the automatically created rigid body simulations?

The dop import node reads back into the same object the result of the RBD simulation. That result could be the same geometry merely transformed (translated or rotated), or deformed by a sop solver (or by a custom solver), or broken into pieces, or instantiated as many RBD objects, or…

Arguably, if all RBD sim did was to translate and rotate an object, you could expect those transforms to overwrite the t's and r's of the geometry at the object level. Then you would not need the dop import sop at all. But RBD does a lot more than that, and more often than not you end up with different geometry as a result of fracturing and deformation. That kind of result can only be expressed in a SOP. Hence the dop import sop.

I have a feeling I am not explaining this too well. Let me know if I need to give it a second try.

Thanks, I think the explanation was okay. At least I now have an idea what the node is good for.