It's already being done on some EV's [1][2]. I think it less about batteries going bad and more about getting people back on the road quickly. I think it's also risky for end users to be doing progressively faster and faster speed charges. They can catch fire with kids in the car.

Using the linked method the charging and battery testing occurs in a safer location away from occupants and allows for slower charging and less spikes on the power grid perhaps even using more solar power to charge reconditioned packs. Get this process fast enough and people will demand EV's because they can get back on the road faster than using a petrol station.

It's also about staying current and staying green. As more efficient batteries come out in a few years, one can swap out and be more green and have more range. That battery pack is a massive investment and this would keep that investment strong. Most people are not going to voluntarily fork out another $15-$50K depending on vehicle and will just let their existing pack age out.

[1] - https://www.youtube.com/watch?v=-5BPL4Nm1q0 [video][8 mins]

[2] - https://www.youtube.com/watch?v=1kZgG58zz8U [video][2 mins]