I'm sure mouse latency is a big issue for iPad Mini users.

I know there's a sizable contingent of people who just think a bigger number is better, but realistically this is a device for passively consuming text and video content that is typically around 30 fps anyway. Why waste the battery power on faster refresh?

The ProMotion screens have variable refresh rate depending on the content displayed. 10Hz to 120Hz for iPhones and 24Hz to 120Hz for iPads. So in theory the power consumption should be even better than a regular screen for static content like reading text.