A friend and his wife went to the inauguration or tried to. They got there at 8:45 am and could not get in. It took 45 minutes just to cross one street because protestors laid down on it and the police only had a few street crossings/entrances available. The spent 1 1/2 hours inside the Reagan building going through security and it was close to 12:00 by then and police said it would take another 2 hours to even get to the Mall through more security check points and long lines(2 blocks away)so they watched on TV.
In a nutshell he feels the numbers were down because it was way to difficult and time consuming to get to the inauguration and people just gave up and went home or were left in long lines.
He said in their area there was 10 of thousands of people lined up but were left in bottle jams. Called it a giant cluster f&&k in terms of organization.