The Benefits of Participation

Something that's been on my mind for the past couple of days.  When does participation within a quest stop being fun, or a lack of participation within a quest become challenging?

Suppose that there is a quest for a key to unlock a treasure chest filled with assorted desirable rewards.  The quest is open to and accessible by everyone.  Here are five variations of the same quest.  In all examples both the key and chest vanish after accessing the rewards.

• The first quest is to unlock the unguarded chest with a key.  The key may be freely obtained from an NPC.  Anyone in possession of the key may unlock the chest.
• The second quest is to unlock the unguarded chest with a key.  The key must be created by an NPC, and the player supplies the raw materials.  Anyone in possession of the key may unlock the chest.
• The third quest is to unlock the unguarded magic chest with a custom-made magic key.  The key is made by an NPC, but it is customized to the player providing the supplies.  Only the person for whom the key was made may open the chest.
• The fourth quest is to find the hidden magic chest and unlock it with the customized magic key.  In addition to the customized magic key, the player requires a magic compass to find the chest.  The compass may be created by an NPC in exchange for raw materials, and the compass will point to the chest only when a magic key is held in the other hand.  The compass is not customized to the player who supplied the materials, so it may be shared with other players (but will only work for a player when they hold their customized magic key).
• The fifth quest involves all of the elements of the fourth quest, but the player also needs magical fire-proof gloves because the chest is covered in magical flames.  These flames kill anyone touching the chest not wearing the magic gloves.  Anyone may wear these gloves, but they are destroyed when the player bearing the magic key unlocks the chest.

In the listed examples, the requirements for participation gradually increase.  The first quest has almost no participation requirement (possession of the key is the only requirement to complete the quest), while participation for the last quest is involved-with-a-capital-I.  Assume for a moment that the value of the rewards for each quest were all equal.  Which quest would you prefer to do?

My feeling is that if a player is going to benefit from a quest, then that player should have reasonable participation within the quest.  The activity should be fun and challenging so that accomplishing the goal is rewarding.  In the first quest, any player could pick up the key at the auction house and use the key to claim the reward.  This could be fun, but it is not especially challenging.  The fifth quest is very involved and could be very challenging, but is it fun to jump through so many forced-participation-and-high-requirement hoops?

The answer isn't clear.  Each player has their own barometer for what is fun, challenging and rewarding.