I know this sounds like a dumb decision for executives to make, but hear me out.
Most people are able to tier up from Unique to Legendary potential on their items within 19 black cubes or 38 red cubes (according to cubing statistics).
But some extremely unlucky players who may have been bugged from the system, maybe system thinks the item is already Legendary and prevents tier up, have to spend tons of cubes to no avail. These players will rage quit and find another game. Personally, I have spent over 100 black cubes on my Unique potential pendant. Without knowing there isn't a guarantee, I'm reluctant to buy cubes or NX. I feel like the system hates me and that I should just quit.
So why not add in a mercy system for cubing?
After a total of 50 black cubes are used on an item, there will be a 20% bonus chance to tier up (4.74% from U-L will be 24.74%)!
If the item fails to tier up, it goes back down to normal tier up rates.
Then after a total of 100 black cubes are used on an item, there will be a 40% bonus chance to tier up (4.74% from U-L will be 44.74%)!
If the item fails to tier up, it goes back down to normal tier up rates.
This could repeat until there is a 100% chance to tier up.
As for red cubes, the same can be done but with a 10% bonus chance for every 50 cubes (2.37% from U-L will be 12.37%).
If the item fails to tier up, it goes back down to normal tier up rates.
This could repeat until there is a 100% chance to tier up.
During Double Miracle Time (DMT), just lower the number of cubes required for the Bonus tier up threshold.
This type of system would retain some players and incentivize players who have previously rage quit from cubing.
If this is already part of the system, then I apologize for this post and ask Nexon to disclose or increase the actual rates for the cubing mercy system.