User blog comment:ChickenRave/Moai, the Mad Better/@comment-3148314-20150618012506/@comment-26030737-20150618180940

I actually made such a long cooldown for Cash In, so Moai has an actual reason to kill a lot of minions. One minion killed freezes one panel on his Deadly Slots, three frozen panels representing Cash In refresh all of his spells' cooldowns. Including the ult. Its cooldown is also very long so Moai can store a lot of Jackpot killing blow bonus stacks before collecting the Mad Better's gold when it's worth it, or save the spell for when the player thinks there's enough in the bank. It's all about deciding when is the right time to cash it all in, whether the spell is ready thanks to the Slots or simply because it's off cooldown like any other spell.

Now for the Dizzy Roulette, I think its size as I imagine it is enough. It only deals damage when the Jackpot effect is triggered, and it's an excellent crowd control effect in early game (when champions struggle to get away from skillshots because of their low movement speed) which is compensated by the difficulty to land skillshots, induced by the spin effect. Making it an ult would force me to put the damage without any condtion to make it a decent ult (since you mentioned them, Amumu and Zyra's ults deal damage too) and the Jackpot killing blow bonus should be bigger than it is right now in order to make it relevant for an ult.

Leaving Cash In as an ult allows Moai to collect the stacks he gained before level 6, giving him a greater power bump at this level. It also allows me to keep a very interesting attack speed bonus for the spell's passive effect, which would need to be significantly reduced if it was a basic spell.