We're talking about Playlist and Playlist Groups here, so there's no way to do that. I'm not sure about you, but every playlist I have under some Playlist Group should have the same columns as the parent.
Absolutely, positively
NOT. Almost NONE of mine are exactly identical. The only exceptions are my sets of "smart mixes". All the rest don't follow that pattern at all. I would say that they usually are similar (maybe very similar) but almost every one has some kind of individualization specific to their purpose. These individualizations also follow patterns, and often amount to moving columns closer to the front, or hiding individual columns with redundant data. So, the ones that change, are often small changes.
So, before, I'd push a new, better column layout from the Parent down the stack, and then I'd go through and tweak the individual children to be "just so". This was quick because it was targeted. It'd be even better now with Profiles, because I could quickly update a particular "individualized" profile (by making one exemplar after pushing the parent change down the stack, and then using the profiles to clone it over and over to the other places it is used).
In other cases, they are identical column sets "underneath" but the view doesn't show columns at all, and is in Thumbnails mode (I always have the Tag Action Window set to Column Display order, so I use this method to structure that even for Thumbnails or Category views).
I don't really care if they inherit by default if created out of whole cloth by creating a fresh view or Playlist, I suppose. That would be convenient too. So long as they don't "force" copypasta-ed Views and lists to take on these characteristics when moved around.
But, I want the push-down-the-stack, so that when I do change my "General Audio" column preset, I don't have to apply it 386 times to all of those "Mixes" smartlists and views.
I mixed terminology between Playlists, Playlist Groups, and Views because, in most regards, the only difference between a Smartlist (and a Playlist Group) and a View is that they don't show the Panes/Categories, they must live under the Playlists item in the tree, and you can't explicitly set the "Files to Show" search for a Playlist Group (it always shows all of the files in the lists that it contains). I skipped a few things there, of course, but as far as column order, view styles, inheritance, and all of that, they're the same exact objects.