There’s an even bigger lack of inheritance down the hierarchy — when you have four movements marked as part of a symphony, unless you re-add the composer, those parts don’t get displayed (or tagged by Picard) with the composer.
I personally copy the more important relationships (like composer) over. If it’s to the tune of X, then I copy X’s composer over (but not, of course, X’s lyricist if any). I also add an arranger and possibly another composer. And a new lyricist. (Well, most of the time I do—I am lazy…)
I really, really wish works inherited relationships from linked works. There needs to be a way to specify which relationships from which works, as sometimes (e.g., not wanting X’s lyricist) you don’t want it. And what to do if X gets a new relationship is an interesting question.