Why not increase rarity drop rate based on party size?
I frequently do full T3 Arcade Runs to nab Radiants at d28, but the drop rate there is still too low--there's nothing more frustrating than doing an entire d28 Treasure Vault and getting only Shining Fire Crystals. This happens rather frequently, and often leave a 30 minute run with only 3 Radiants, occasionally with none, and on the high end about 12. The situation is practically encouraging me to only do Vana runs for better crown pay out along with the same (or better) Radiant output.
This could be avoided by somewhat "forcing" larger party runs to the core as a means of increasing Rarity drops (and only rarity--not crown or heat). Such that a full 4 person party would yield the same Radiant drop rate as it did when the forge system first came out.
This would not be easily abusable market-wise, since all Rarities are bound, you would need to be able to run 4 instances of SK simultaneously. Not to mention you would only get Eternal Orbs in T3, which are no good for an alt.
It is a system that encourages team play by increasing the # of rarities players get. Dead players still don't get any loot that appear while they are dead, so there's no worry of stragglers/freeloaders.
Tons of suggestions to increase drop rates. (Most trolling around when the famine started.)
Bolded are ones I like, but do not fully fix the problem.
Nostalgicreaverbot's Craft-down Orbs
Summary: Allow orbs to be crafted down to lower *'s.
Mawashimono's Craft-Up Fire Crystals
Summary: Allow fire crystals to be crafted up and down.
Malignant-Manor's Item Strength
Summary: Make lvl 1 5* items equivalent to their lvl 10 4*.
Pataponex's Heat Capsules
Summary: Storage of excess heat.
Stromling-Savior's Lower Crafting Cost
Summary: Energy prices remain the same, cost of crafting increased.
Skyguarder's Lower Radiant Cost
Summary: 300 energy per 100 radiant fire crystals.
Lucarionation's Lower forging cost
Summary: General energy suggestion, which includes lowering the cost for buying fire crystals from supply depot.
Dr-Charizard's Craft Up Crystals
Summary: Be able to craft 5* fire crystals.
Honeydieu's Vender Fire Crystals
Summary: Sell fire crystals to vendor or allow unbinding.
Danielflame's Selling of fire crystals
Summary: Allow the sale of excess fire crystals.
Chrome-Zero's Fire Crystal Drop Booster
Summary: Item that boosts fire crystal drop rates, locations, and a bunch of other things.
Jett-Black's Get Rid of Crystals
Summary: Revert back old heating style completely.
Redlawlsy's Heating on an elevator
Summary: "Forge" locations everywhere, specifically on elevators so one item can gain multiple levels on a single depth.
Imtn's Fire Crystal Change
Summary: Have tier specific fire crystals, instead of item star count.
Megawatt-King's Make the forge optional
Summary: Increase heat required to level an item, but make the use of fire crystals optional.
Doctorspacebar's Inert Fire Crystals
Summary: Lower cost fire crystals that require heat before use in the forge.
Skyguarder's Cheaper Radiants
Summary: Lower SD cost for radiants.
Zethalan's Increase Orb Drops
Summary: Increase orb drop rate.
Pwnswag's Forge Machine
Summary: Forge not tied to arsenal, instead a new station to forge (that appears on boss depths too!)
Klipik-Forum's Crystal Tanks
Summary: Tank that generates fire crystals with heat.
Paintool's Forge Pass
Summary: Forging pass to bypass/decrease cost of forging for a certain amount of time.
Edit: Will perpetually update as I find more threads in the suggestions subforum (other subforums ignored). Threads sorted by node #.