In the rainy Pacific North-West, one regularly needs the defrost on the windshield, but does not require the heat that is included when the Model S front defrost is selected. Would love to see an option (like on standard vehicles) where the defrost setting is temp independent.
With v4.5 software, Tesla added a two-level front defrost. You can select cabin air only or heated air.
I'm missing this feature on my Nissan Leaf so badly that I'm going to hack the control panel to let me disable the heating element but still run the defrost program with just cold air. This feature is a must-have!