I agree. It is useful to maintain the distinction between windchill and actual ambient temperature.

For example, as I sit inside and type this, according to the weather service the outside ambient temperature is +11 F and the wind is 29 mph with gusts to 43. That means for someone walking in the open, the effective temperature ("windchill") is about -12 to -15. However, should that person find some shelter from the wind, perhaps by stepping into a thick woods, the effective temperature would rise to +11 F. On the other hand, if the ambient temperature were actually -12 F, and that person stepped into the think woods, the effective temperature would still be -12 F.

It is rather obvious to say, but when dealing with windchill, anything that protects you from the wind makes it warmer. Just putting on a thin shell garment (with no additional insulation whatever) makes a big difference. On the other hand, when dealing with ambient temperature, you really need more insulation!