Because there is undefined behavior for shared edges.

I thought common verticles shoud receive average.. Ok.
Big thx for great plugin. It's already ten times better than Blenders "Data Transfer".
Realy thanks for patience:)

It seems to me that this is a strange duplication of functionality.

You are right. I was just trying to explain :)

I just came with another suggestion!!!
Allow for "face" direction with "Split mode" together. Maybe I'm wrong but it could improve creating verticles normals where some normals are sharp and some are not, so they don't influence other faces. Like in the picture.
(To be honest i don't know if this is good, but creating normals like in the picture took me ages…)

Last question. Why cant we select few faces at one for "face" mode?

What Oscar is trying to say in 4 is:
Left part of the image show normals where cap faces are done by "Face" Button.
To produce good normals for ring i had to add a loop in the middle, and copy/paste every vertex normal to its neighbour!! I know- I could do this here by second mesh, but this is only an example.
It would be cool if i could just said: make normals of these verticles planar on Z axis.