I think having one motor per wheel is very useful in terms of all-wheel drive (and braking) -- being able to selectively apply varied amounts of power to each wheel depending on conditions.

Not sure I'm convinced by the torque claim -- we've seen cars skidding / losing traction in both scenarios (accelerating and braking). ABS brakes were developed specifically to prevent that (and so was Traction Control).

My experience with electric vehicles is limited to a Boosted longboard, so take this with a grain of sand -- but it seems to me that electric motors are as effective at braking as they are at accelerating.

I'm thinking in terms of f=ma, or the equivalent in terms of torque. I can live with my car getting up to highway speed within a much longer time duration than how quickly it needs to slow down if I hit the brakes. So the brakes need to exert more torque on the wheels than the motor does.

Putting a motor on each wheel could have some performance benefits, but I'm not sure I'd pay for it if I could get a single-motor car for cheaper. I'm talking about "econo box" performance, which is all I want anyway.