I can understand where you're coming from. We have it balanced like this because when things get really hairy, you may want the trains to go a more slowly so you have time to make adjustments. As funny as it sounds, it also breaks a bit of the mesmerising and relaxing part of the game if we speed it up too, and that is part of what many people really enjoy about the game.
We have the Fast-Forward option in the clock menu to let you speed things up when you'd like to. Again, this is one of the challenge spots where it might be a better idea to rearrange your current set up to help alleviate the trains on longer tracks.