The fact it’s a long game isn’t an issue, the problem is that it’s long and bad. A winner is usually determined pretty early on but then there’s still half an hour of random rolls as everyone slowly loses their money. That’s why house rules are mostly adding safety nets, the game’s already over and it’s just not fun running around a board watching your numbers go down. Since house rules don’t change the core gameplay they don’t fix the game and just make it drag even longer.
There’s some very good long games and some very good short games, how long a game is doesn’t determine how good it is.
This is true for all public holidays in the UK, there’s a (usually) fixed number of public holidays but the dates are flexible.
They’re also included in the minimum 28 days paid time off too, meaning if you’re a full time worker and have to work on a bank holiday your employer is legally required to offer an extra day off somewhere else instead, either a fixed date or added to your holiday allowance. Conversely, the “extra” day off you get when a monarch keels over may be subtracted from your holiday allowance for the year. This is also why my employer is allowed to follow English bank holidays despite having next to no presence in England; the number is fixed but the dates are not.