With this your suggestion, the casino will be at the losing side whenever the gambler set the cashout. And the bookmarkers will look for alternatives way to bypass that feature. Either they will make the cashout very small or remove the cashout features in most of the game and only in specific games which they know that the percentage of cashout will be minimal. Though the proposed suggestion is good but I don't think casino bookmakers will implement it because they are also using that to make money.
For us we should try to avoid overly involved with how casinos run their business, I am sure that most gamblers will want to be on the winnings side or at least minimize their loses but in the end, we should know that if we want to have a gambling platform to at least play on, then we have to support those casino's to at least sustain their operation.
So we shouldn't propose what we know can kill the casino as a business, we must apply every possible caution when we are making such suggestions.
Sometimes there are people think about unimaginable things that impossible to implement that's why they should do some realistic check before suggesting those things come up on their mind. Since there's nothing gonna happen with bad suggestion especially if the casino is on disadvantage side with it.
Also for sure casino won't implement anything that can kill their businesse.
But there are really good suggestion posted here and if casino owners could read this thread maybe they can implement some of those especially those real beneficial to their gamblers.