Mainly, it just isn't generally true that we should always want trains to avoid longer paths to the same blocked track like in your idea. Given a layout like you have in your screenshot, it is entirely reasonable to *want* the second train to use the loop as a buffer if there is a blockage: If the second train is long, then taking the loop will free up track behind it, which might be important to avoiding jams in the rest of your network. I would not be content to add heuristics that take away opportunities like this.
I am, however, working on an option to modify how a train considers detours when it is stuck in traffic. I believe this will help for your playstyle.