Great post, thanks.
NFL is boring if you haven't watched it before and it has no meaning. EPL (soccer) gets the biggest crowds and TV, yet to me is still boring even though I played it. The main reason for support is allegiance to clubs, being a Man U or Liverpool die hard.
In Australia, sports are even provincialistic....AFL is mainly supported in Victoria (it used to be VFL). Rugby League is NSW/QLD (mainly NSW), Rugby Union is NSW/QLD.
Every sport is fighting for TV eyeballs and are forever expanding into other areas, and investing big in creating teams interstate, getting a following, spending grassroots money hoping that kids take it up.
The crowds are only a secondary issue, only there to create some atmosphere and to make the TV coverage imply that there is a huge following. They even sell tickets based on that, and one basketball owner even rang up mid match and asked the staff to move people into one area instead of scattered.
They are all after your TV $$, now they are after your gambling $$ and alcohol $$...there is little of supporting grassroots sports for its benefits, but rather for their benefit