I understand what you're saying and can't argue with your logic, but please remember that Centova Cast is just a control panel... it does no audio processing itself. The crossfading capabilities are provided by the source software (ices, sc_trans, etc.), not by Centova Cast. So until/unless such a feature is added to the source software, Centova Cast isn't able to take advantage of it.
That said, if such functionality is ever developed we'll most certainly add the relevant UI elements to Centova Cast.