Why implement the halving as a step function every 210k blocks instead of continuously reducing the block subsidy each block? An infrequent halving event that poses a bit of a shock to the cashflow of miners seems more risky, in that it will suddenly bankrupt a chunk of the miners with insufficient marginal profitability, rather than blurring out those bankruptcies over a larger window of time.

More concretely, rather than having the block subsidy = 50 >>= floor(height / halvings), it could simply be 50 / 2^(height / 610k).