Pretty much the title.
The majority of my DDO playtime is spent playing with with a Static Duo (My Friend and Me) and a Full static group (MY PnP Group) most of which are Premium players with a varied amount of purchased quests...One of my friends and I for example have been playing much longer than the rest and have all but 2 adventure packs so pretty much everything is open to us so to when Duoing we really could care less
On the other hand when gaming with our larger static group were pretty lost on what quests we can and can't do...it's pretty much trial and error which is a PITA and quite frustrating as the ages of the people in this group as well as their income are quite varied (Between 17-30) and buying turbine points has to be planned and agreed upon by everyone so they can't just buy adventure packs whilly nilly.
Now if the adventure compendium actually said whether a quest is F2P, Purchasable or Owned, it doesn't need anything super large just a small icon for each quest (see below) than this would not only make planning which packs to buy more convenient it would also make actually questing alot less frustrating so Win-Win for both Turbine and the players
Here's a quick pic of what I'm thinking
Afterthought: Maybe add a 4th symbol to show if an particular purchasable A-Pack is on sale)