Your idea was actually what I had in mind for the extension. But, it is technically hard to do this, in order to show the videos as a row separately, it needs to collect the videos from the watch later page. And there is no way around this.
This is a problem because the users have to go the watch later page wait for couple seconds and go back to their homepage every time if they want the row to be updated with the latest videos. This is whole load of work with diminishing returns because when people have access to recommended videos the watch later list will just keep growing.
Hence, I had to make the extension the way it is currently.