I'm going to have to sort of disagree, has coverage shrunk? Maybe on local (and some cable) TV broadcasts, but everything seems to be shifting online. And I think there's actually more coverage now, the problem though is that there's not really a central location, so to speak. Alli Sports has really stepped up with the Outdoor series though, have you ever seen this?
http://www.allisports.com/motocross They'll stream the first moto live online (with commentary) and then CBS, NBC, or Speed picks up the second moto on TV. Plus here you can actually watch past races, full length as well.
http://www.allisports.com/motocross/archive
I know that last year Speed also had full length videos of the lites class (not sure about the 450f's).
You're right and I don't like it.

It's becoming to corporate and it's very hard for privateers to make it.
Around here bottom row seats are $45 (plus $10 in fees venue

) and top row seats are $10 (plus $7 in fees)
http://www.ticketmaster.com/event/050044F3AD7EA7D1?artistid=821673&majorcatid=10004&minorcatid=25