Great topic of discussion. I am a huge fan of 80's and 90's drum corps. The main thing about those shows compared to now is indeed the lack of emotion in the musical scores, and that a tune is rarely given more than 6 bars before moving onto the next musical phrase. As an example... Star of Indiana got it perfect... they played a whole tune, were technical when required, but simple when it needed to be, very emotional and fantastic visually.
One tune that stood out for me this year was Spirits ballad. They did a great job and shows it can be done.