None of my teachers ever had stripes on their belts and we had no problems lining up. I also think putting stripes on one's belt takes away the opportunity to work on our noonchi, our perception abilities.
However, more and more I do see schools adopting some sort of stripe or recognition system for dan holders. Some use stripes, others use different color thread for different dan ranks, and others use a combination of the two. I asked one of my commercial instructor friends why he chose to do that, and he said distinguishing between the dan ranks gave people more incentive to stay longer/pay more money. It was basically a marketing thing for him, a customer driven innovation, because his students like it, even though he didn't particularly care for it. But you have to do what you have to do when running a commercial school.
Of course, he explained it differently to the students, but that was his real reason for adopting that stripe system. He got the idea from a martial arts business seminar that he attended, the principle being that people will do all sorts of crazy things and pay big money for visible trinkets that make them feel special.
