Bits are smaller than microbits and bustabit like platform are allowing minimum bet of 1 bit that mean 100 satoshi only from the day one and there are still many platforms which allow 1/10 of microbits to bet on single round. Casino will adjust minimum bet amount with increase in bitcoin price but they might not keep changing it everytime when price will bounce up/down by few thousand dollar.
yes things should be adjusted following the recent situation , a casino can not keep their minimum bet at 0.001 or so where bitcoin has high value . they can not ignore about it for sure , it is not fair to force people making that bet as the minimum.
nowadays are the right time to make the smallest unit of bitcoin as trends on setting the minimum bet.