You can't wear headbands and look okay with overgrown bangs. Hair gets stuck in your eyes, or worse, your eyelashes. Your forehead gets itchy. You have to spend extra time blowdrying. This reduces laying-on-the-floor-staring-at-the-ceiling-before-work time, which is very valuable to your mental well-being.
I need a bang-trimmer in the train station, like a shoeshiner.