The new relationship editor clearly needs a lot more screenspace than the old one and there have already been complaints on IRC and in the community forums even before it has been announced to a wider audience (so you can imagine the possible outcry once it is announced).

Most of the space is taken by the "Add another entity" buttons which are displayed for every link phrase group. It might be comfortable to add another relationship of the same type without having to select the relationship type, potential dates and other attributes again. But I think this is rather a rare use case, so it shouldn't make adding a few additional relationships to a release which already has a lot of relationships less comfortable (lot of scrolling necessary, less information fits into one viewport).

I had already discussed this issue with bitmap on IRC a few months ago, but didn't found a better solution than adding a toggle to hide them all back then. (I had also experimented with making them appear on hover only, but that's a UX nightmare.)

Having thought about it a bit more, I would even claim that most of these buttons will never be used, except for the one of the most recently added relationship. Maybe only showing these buttons for relationships which have been added/modified in the current editing session would be an acceptable compromise? Edit: At least for the release relationship editor this would make sense - for other entity pages, which are less crowded, these don't disturb as much and are certainly useful.

P.S. An extreme example where it is very unlikely that anybody will ever add another relationship with the same properties are e.g. spoken vocal relationships with role names, where each relationship will have a different role name (unless it's a weird story):