100% agree with the original post. The UI has been pretty much the same for a long time, with only minor changes, some of which actually made the spectator UI worse. For example, as mentioned, the timing board size takes up almost a 3rd of the screen. Having the ability to customise and resize elements of the spectator UI would be a massive improvement.
Another improvement could be the ability to have more control over what camera views we can use, as some of the current ones are not very good for live race streams, i.e. the camera view that is just behind the drivers head - this view is mostly blocked by the car and the halo and when you commentating on races and the camera switches to this you are most likely not going to see any action.