This was all part of the "EVs are only suitable as town cars/ commuters" mentality. Ridiculously short ranges, batteries that died after 4 years of hard use, crappy fast charging, etc etc. The side effect of the battery not cooling down is it meant you couldn't fast charge the pack twice in one day. Not that it mattered too much because with the range offered and speed of charging, few people wanted to drive more than the base range of the cars.The original Leaf was NOT air cooled in 2011. It was sealed cells inside sealed modules inside a sealed pack inside the shell of the car (floor of the cabin and the aero shell below). It radiated heat slowly taking more than 24 hours to come down to room temp if in a truly hot climate.
Not a single EV other than the Leaf went with a pack that is designed to avoid airflow and has no phase change or liquid coolant of any kind.
To tell you how bad it was, I can charge at 120v (1kW) at 80F-100F, the pack is above ambient temp when I unplug and when I drive home the internal pack temperature rises as I drive at highway speeds. Doesn't matter how fast you drive. No airflow makes it to the pack to actually cool it.
They kept that brain dead tactic with the 24 kWh, 30 kWh, and 40 kWh packs. It wasn't until the very recent (2019 or newer) 60+ kWh leafs they did anything about cooling different from the orignal sealed pack.
Literally the opposite tactic of Tesla where the pack is heated and cooled as much as needed for optimal performance. From 2012 Model S to every car Tesla has made since there has always been a strong method of managing heat (despite not pleasing some track enthusiasts, they at least had functional designs that protected the pack).
They didn't cool the cells because a city car wouldn't need fast charging.