One could argue, which we do here on DCP, that in any given year the DCI champion was not the best corps that year. They are the best corps that night as decided by the judges.
While I've only been to Championships a few times, generally I think the judges have made the right decision.
Many years it's been so close, it's really hard to say which corps is best. But the competition aspect is part of the activity. It's one of the biggest motivators for the members, the staff, and design team.
Whether Kingsmen were the best that year or not, you can't say they weren't a great corps.