Why don't a lot of programmable controllers have a current throttle?

This might be a stupid question, but I'm genuinely wondering. There are many cheap programmable e bike controllers. You can change the max current output through an app or through a computer. If it's so easy to change the max current output, why is the throttle on most of them still controlling the speed and not the amount of torque or current? Wouldn't it be simple to implement?