We wanted to add this feature to GSX objects but, as Kevin correctly pointed out, it would be mainly to do accessory functions, like opening a door of a vehicle, not to call services because they are "services", not individual objects. Sometimes a service triggers the movement of many vehicles, sometimes it doens't, so it might not always clear what you wanted to do.
However, the function is not available for ground vehicles, so we cannot do it as easily as user airplanes, it would require custom mouse handling, like in the GSX editor, but custom mouse handling has SOME cost on fps, that's why we restricted it to the editor, when fps is less important.