Push-pull output saves a pull-up
Because the output is push-pull, the reset signal is actively driven high and low. That eliminates the external pull-up resistor required by open-drain supervisors, which simplifies the BOM and frees up one resistor placement per reset line. The active-low reset polarity is the standard for most MCUs and SoCs — the supervisor pulls the reset pin low during undervoltage and releases it high when the supply is stable and the timeout expires.
For new designs or ongoing production, there is no near-term obsolescence risk to plan around.