I have watched Double AA teams beat MLS teams in the Open Cup. Some teams put a premium on the regular season, others want to win the tournaments throughout the season, others go for both.
The reason i bring that up is the separation in talent from the MLS down is not as great as it is Europe. A game here or there can be decided by the bounce of a ball. Over a season, the MLS teams will reign.
American soccer is still growing and trying to find a style. I frankly don't give a shit if Billy Six-pack, in his Ohio state jersey and Dallas Cowboys hat enjoys soccer or not. I don't measure my enjoyment by how many people are with me.
You should try going to a Carolina Hurricanes playoff game. The arena is packed and many of the people there have no clue what the offside rule is.
American sports fans, on average, want to be part of something special. The NFL is "special" because of the gambling, fantasy and limited number of home games. The World Cup got good numbers because it was the World Cup.
Baseball attendance is down, so is tv viewership, because there are so many games. Each game is not "special". Attendance and viewership will go up in the league championship series and the World Series.
There were over 70,000 at this game, because it was special. There are many soccer fans here, but they are looking for a reason to go. Seeing Brian Ching play is not gonna cut it.