Why? The hot spot doesn't provide carb heat (that's provided by the thermostatic air cleaner), it provides intake manifold heat, which is a good thing, not a bad thing -- see here (see the video!).
Not quite. The hot spot is for carb and fuel mixture heat. If this was not true, it would not have been designed into the engine from the beginning. The thermostatic air filter eventually provides warmer air that helps the fuel stay suspended in the air better.
For those of us who don't live in the rust belt and points north, there is such a thing as excess heat. Here at the Edge of the World, we have lots of it. Because of the proximity of the intake to the exhaust ports, the intake on the /6 will heat up without a supplementary source.