Well it does nty have so much to do about reordering nodes but rather it offers a service for you.
See the shape is allocated in the shape node. Now shape node contains 2 things it contains a input mesh and tweak array that contains the changes made since it arrived. Now a teak node offers the user a option to reroute the tweak to a different part of history. So your point edit goes at th tweaks location in history instead of last. So you may be editting the shape before deformation.
Secondly it sends the rather naive reorder inputs dialog a signal that after this its a straight history. So the gui knows all is clear pickcings. It might not be tough, and you can allways manually reorder stuff as you like.
third it acts as a half of a shape node
QUOTE
I'm writing an automatic rig and I won't change the order of the different deformations. So my question is, if it's possible to delete the tweak-node without having problems afterwards?
who said its about what you want. its about what some user may end up doing. DOnt design stuff with the clear intent that you know everything about what will be done. Know that your so good that it does not matter,, never suppress usage possibilities, just because you cant anticipate them.