Slide to end would be pointless because why slide when you can just press? It makes sense for answering because it's in your pocket or what have you where it can be pressed by accident. That being said, with the recommended settings, the screen is off once you're in a call. In order to end a call, you'd have to turn on the screen using the hardware button, then slide to end... this doesn't make sense when I can just press the hardware button to end it.
As for the slide to answer to speaker... no one wants to hear you on speakerphone by accident at the worst of times
