My thought is that you didn't research what you're talking about very well. The "recent extreme marching band promo" wasn't a commercial, it was a google ad. There is no audio, there is barely visual. DCI did what it needed to do with it's limited amount of space, because there is no way you are going to explain the difference between marching band and drum corps in a google ad.
Honestly, I don't think that DCI is really that concerned with building a fan base within the general population, because IT'S NOT GOING TO HAPPEN. Drum corps is NEVER going to be mainstream. You know what fan base they WOULD like to expand? The millions of band kids around the country. They are the future of this activity, not the general population. Now is a marching band kid going to be more likely to turn to ESPN to watch marching band, something they identify with and actually participate in, or to watch "drum corps", something that a LOT of them have never heard of.