Parts of this idea is fragmented out across several poorly-worded requests, but I wanted to collect them under one banner, as they are a single functional request.
Collections should have 2 new toggles/settings per-collection.
1. "Count all nested bookmarks in the parent count" [ON/OFF]
2. "Display all nested bookmarks in the parent" [ON/OFF] (This is only enabled if #1 is ON)
This can lead to several very useful situations:
A. I want parent collection to both display and count all nested bookmarks.
B. I want a parent collection to count all nested bookmarks in its 'bookmark count' but not actually display them in the parent collection view.
C. I want the parent collection to neither count nor display any nested bookmarks, like the existing functionality.
There could be some UX element that clearly denotes which of the displayed bookmarks are from the parent collection, and which are being displayed because they are from subcollections.
An alternative to the toggles would be to implement a separate taxonomic designation of "category". A "category" would be like a collection, except it would not allow adding bookmarks directly to it - it would be only for grouping collections. The "category" would automatically count all nested collections, and display all nested bookmarks.
You would need to permit multilevel "category > category > category > collection > collection" nesting, or else it would be very limiting.