Some debugger plugins use the layout mechanism to create views which are arranged like panels, but this is indeed quite hacky and may interfere with user layouts of "normal" views. What I hate most with it are the tabs which are displayed on top of such panels as they are not really needed if each focus group contains one view only.
Besides the fact a debugging interface is somewhat more than being able to create dedicated panels, I agree with you. A more powerful API to create panels, like in atom or VS Code would enable new functions here and there.
But I guess it won't be part of ST3 but maybe ST4 in the future.