People do not go to the nationals for two reasons... One, they are not invited (since for this comp only allows a certain percentage of people to enter) and two, if they are interested in seeing the dancing presented at the comp. nobody will pay to see something that they perceive as too expensive, too boring, or too obscure. Thinking that having an empty ballroom is better for they competitors than a. Full one means that no excitement is generated, so people tend to think of it as a hump to get over in their dancing rather than a highlight.
And thinking that spectating an event is a duty is foolish thinking on the part of those involved with selling the event to the. Public. Pricing people out of spectating means many times that competitors do not show up except for their events, which contributes to the emptiness. They very people who would be most excited and interested wind up sitting in their hotel rooms because to drop in on events costs a couple $$$ they might not have. And it is a hard sell to a public that expects a rocking event and not a quiet, tense hotel ballroom devoid of energy.
Baltimore is a nice city with some of the best restaurants on the midatlantic, but the area that the nationals is held is populated by fast food and chain restaurants and is not really very interesting to visit more than once... It IS more walkable than la, but the question is of course 'walk where'? Plus, many competitors dance and prepare outside of the more normal tourist schedules. Day trips and the like are not usually practical when you dance at midday or have rounds in the evening that you must rest up for.
It is a thankless task for sure to create events that become desirable, but it can be done...USA dance has had an athlete drain for the last few years as folks choose to skip USA dance for more competitive events, and this also makes nationals a more iffy proposition when top dancers choose alternate paths. New leadership is headed by a president who has spearheaded a big, boisterous and successful competition in the MAC and hopefully they can inspire and change the mindsets that have made nationals a loss financially and not a 'must do' event...