I think the root cause is just the market asking for oversized battery packs. That enables both the large instant current capability and high charging speed, without requiring too much additional cooling (it's all spread out). You still need to add the oversized current driving capabilities in the electronics that you wouldn't strictly need for fast charging, which is DC and bypasses most internal electronics anyway.
I think this comes down to market economics more than product design. Many manufacturers have been production limited by cell supply for a long time. You _could_ make cars with extra large battery packs for those who live in exceptionally cold climates, but it's a limited market, and you'd be taking away cells from shorter range models. E.g. you're likely to make more money selling 5 cars with a 60kwh pack than 3 cars with a 100kwh pack.
