My base example will be on Crystal Tower raid(s), but the same idea can be applied to the Binding Coil(s) of Bahamut.
In general we have 6 Types of armour sets (Tanks/Healers/Ranged-DPS/Hand-DPS/Magic-DPS/Dragoon-DPS) by 6 pieces each, total 36 items. If we assume all chests can drop any loot regardless of boss, there is almost 3% chance of any piece of armour to drop. That 3% is shared between tanks/healers/DPS depend on the dropped piece.
Worst is 3% for 5 DPS, that’s 0.6% chance of getting the item. Four chests yields 0.6 x 4 = 2.4% if that DPS is a favorite of God of Randomness and Luck. That means a person is required to run about 50-60 times more or less to complete a set!
Since the Crystal Tower (CT) raids: Labyrinth of Ancient (LoA), Syrcus Tower (ST), World of Darkness (WoD), are being:
1. deserted due the fact that the gears are outdated (i80, i100, i120),
2. in addition of the progression introduced in Heavensward, and
3. People growing bored to run them anymore (especially with that random drop).
Thus I suggest that the looting system in CT raids should be demolished and exchanged with Daily Tokens* (Labyrinth Tokens, Syrcus Tokes, Darkness Tokens), where killing each boss grants every player in the raid by one token. These tokens can be exchanged in MorDhona by NPC: Aelina (probably) for the armour drops. In my opinion 6 Tokens is a good price for each piece, 3 tokens for the belt (less wanted).
*Note: Daily to give a chance of random people to run it all around the week, not farming everything in one day.
This same idea can also be applied on The Binding Coils of Bahamut T1 to T13, but –of course- adjusting the pricing for the drops since there is one boss per Turn.
Add your thoughts to this thread, SE should be listening.
TL;TR: Remove loot from CT(s)/Coil(s) and give players Tokens that can be exchanged to any piece of thier choice from an NPC-vendor.