Hi I have seen the package:

https://github.com/justbur/emacs-vdiff

And I am wondering why ediff does not behave (a bit more) like it by
default.

It is simpler to use, faster to locate differences (it hides equivalent
lines when they are too may), we don't need to learn extra commands to
scroll; aesthetically it looks better and 99% of the users I know are
used to vimdiff...

Essentially the main missing features in my opinion are:

1) The addition of empty lines (filled with ---) to keep the same lines
in both sides.

2) The buffers scroll together with the normal arrows

3) The colors are more explicative.

I added some pictures.

Is it too complex to implements some of these? May I ask the author to
add it to elpa?