Making it an option will most likely not happen because almost all users want the current behavior and the camera code is already complicated enough. That being said, anything can happen as Cesium evolves and making the input more easily configurable is definitely on the long-term roadmap. So it might be an option one day.
In the short term, it’s easy enough to mimic the old behavior in your app. Something like the below should get you mostly there, although some of the scaling code for amounts may need to be tweaked. I didn’t look at the old code to see exactly what it was doing. You could also use this code to offer both in your application if that’s what is needed and provide a toggle to switch back and forth.
var viewer = new Cesium.Viewer(‘cesiumContainer’);
viewer.scene.screenSpaceCameraController.enableZoom = false;
viewer.screenSpaceEventHandler.setInputAction(function(amount){
amount = Cesium.Math.sign(amount) * viewer.scene.camera.positionCartographic.height / Math.log(viewer.scene.camera.positionCartographic.height);
viewer.scene.camera.zoomIn(amount);
}, Cesium.ScreenSpaceEventType.WHEEL);
var rightDragging = false;
viewer.screenSpaceEventHandler.setInputAction(function(){
rightDragging = true;
}, Cesium.ScreenSpaceEventType.RIGHT_DOWN);
viewer.screenSpaceEventHandler.setInputAction(function(){
rightDragging = false;
}, Cesium.ScreenSpaceEventType.RIGHT_UP);
viewer.screenSpaceEventHandler.setInputAction(function(movement){
if(rightDragging) {
viewer.scene.camera.zoomIn(
(viewer.scene.camera.positionCartographic.height *
(movement.endPosition.y - movement.startPosition.y)) /
(Math.log(viewer.scene.camera.positionCartographic.height) * 4));
}
}, Cesium.ScreenSpaceEventType.MOUSE_MOVE);
Hope that helps.