1) Reduce Difficulty Considerably for early waves

The first wave or so should be balanced around people starting out, who only have a wood sword to kill the mobs. The mobs will currently overwhelm any new player in a few seconds
The current difficulty might be fine with people using the iron sharpness swords and 1st-tier diamond armor, but as it is, isn't balanced at all.

2) Increase the drops of the mobs

The earliest waves in this new model would drop the same droppings as they do now. As the "waves" progress, however, more droppings should drop at higher frequencies (ex: wave 10 mobs can drop 3 droppings 40% of the time). Lower Meeble gain of pumpkins by 50% to compensate for increased droppings.

3) Make unlocking permanent possible

Power upgrades would be used to further create progression in the game, since it should be built considerably on that. Upgrades, such as health boost, weakened strength, and resistance, would be unlocked through varying but exponentially increasing amounts of drops, like a tier system. An example would be something like Strength I (+15%) to Strength II (+30%) to Strength III (+45%) and so on.

4) Increase the amount of gears you can unlock by 1

Add one final set to the shop which is the most beefed up version of the God Set.
Armor would have Prot XIII + All other Prot VI + Unbreaking X.
Sword would have Sharpness XIII + All other damage enchants VI + Fire IV + Looting I + Unb. X
Cost: Some really high number of legendary drops, maybe a 6th? tier drop which is unlocked through a boss or something (Call it mystic)

4b) Increase the strength inbetween mob waves

The first wave, as mentioned before, would be very doable with just a wood sword. However, each wave increases quantity of mobs, Mob stats, Mob speed, and Mob Effects (if any actually exist). This would mean that no run can be endless, but progression can be seen as players unlock upgrades and get better gear sets.

5) Encourage more team work

All players that do a certain % of the mob's damage should receive a dropping 0-1 tiers below the dropping that had been looted. The player who picks up the loot will not receive the lower drop.

With these changes, the event could be made a permanent minigame that can be done any time of the day and is a source of income for those who invest their time in it.