Other commenters have similar thoughts but here it is said more directly: the car should not drive differently at all depending on temperature. There is no reason it has to be that way. The motor can regen fine at any temperature. The battery cannot, but dumping power resistively into air heat is one of the easiest things to do electrically, and they could definitely do it.
With one counterpoint being that maybe this is a feature, not a bug, and may save drivers from excessive non-productive braking.
I checked around, and a 2 kW dump resistor is about 3" diameter by 20" length. You'd need, say, 16 of those at a packing fraction about 0.5 for sufficent air flow, so you're looking at a cuboid which is 20" long and 4*3"/sqrt(0.5/0.9) = 16" to a side, or 2560 cu.in. Then you add the fans and the intake and outlet ducting etc. you can probably figure 3500 cu.in. total volume.
For comparison, the Model 3 "frunk" seems to be 28" x 15" x 9" = 3780 cu.in. So you'd have to sacrifice the entire frunk for your resistor pack.
Now where could one get this said airflow in a vehicle moving through a medium that is commonly referred to as air? :)
Heating up the battery with this airflow for a certain amount of time should warm them up relatively quickly and evenly since done via convection too. Now I genuinely wonder if there is a reason why Tesla didn't go with that.
For something that generates a lot of heat when bringing the car (and air!) velocity towards zero, you really need to have forced air cooling available.
With one counterpoint being that maybe this is a feature, not a bug, and may save drivers from excessive non-productive braking.