Likewise, from a collecting perspective if I'm collecting for a set normally once I've accumulated the majority of the set and want to know what I still need the easiest thing to do was:
Got to the database > Advance filter to that set > Sort by Inventory Count and it would give me all of the cards in that set grouped together and I could easily add them to my wishlist/trade list.
Finding out what I'm missing now requires me to look through x pages for where inventory count is 0 for a card. Either sorting like it was or an additional advanced filter for edition owned in where I can do edition owned in [is none of] set I'm looking up.