while withdrawal limits can be annoying it has valid reasons why they are placed. From what I remember reading, one of the reasons is there are gambling regulators that require online casinos to have withdrawal limits as a way to prevent money laundering.
You are right about the significance and importance of withdrawal limits, however, I don't see any logic behind reducing the limit drastically without informing the gamblers or customers which is what they did and that is wrong and there can be no justification given about it. If they had plans to make that change or had decided to do so, they should have at least let the players know that they had made some changes in the terms and conditions.
anyway, I also remember reading that withdrawal limits also benefit the casino as it can protect their interests, as you know if a gambler with a lot of funds can't withdraw all their funds in just one transaction there is a chance that they'll gamble with the remaining fund left on their account n the casino.
They surely do, casinos are always looking for ways they can use to keep their gamblers within the platform and make them gamble more and more because that's what benefits them. When gamblers don't get to withdraw their funds, they will feel the urge to gamble and when they do that, they will most probably lose the money back to the house.