I recorded the BMX races last night out of curiosity. (I've included some HD screen grabs of crashes for your enjoyment; click on them for the full size image.) BMX has been introduced to increase the interest of young people, those who like Xtreme sports. NBC even has a BMX crashes compilation (link broken) for you to watch while you drink your Mountain Dew or get another tattoo.
This is the first year BMX is being contested at the Olympics and I'm conflicted about it. While I support any kind of cycling, in order to introduce this kind of cycling, the Olympic Organizing Committee cut two track events (the men's 1000m and women's 500m time trials) to make room for the BMX events. This was done to conserve the number of cycling events. According to this page (link broken) there are 18 cycling events. Swimming has 34 events. So increasing the number of cycling medals wouldn't have given it a ridiculous number of medals (unless you think swimming has a ridiculous number of events, which I in fact do). Granted, Olympic cycling isn't as popular as Olympic gymnastics, and that only has 14 medals, but at least gymnastics takes place on different equipment. The cycling events range from 40 seconds to over six hours on four different kinds of venues that require very different types of skills and strategies. Each medal rewards a clearly different set of accomplishments. All but two of the swimming events are in the same damn pool (the 10K open-water swim is new this year) with the same equipment, only the strokes and distances change, and the distances vary by far less than cycling. It's not clear that adding BMX is a net gain for cycling in the Olympics, and they could have very easily increased the number of cycling events, in my opinion.
Of course, cycling has the Tour de France every year, while swimming has ?
I think the best thing that can happen is if BMX becomes a kind of gateway drug into cycling. Get the young ones into the sport and then push them into the real hard stuff, like the velodrome and road cycling. Then they'll really be hooked and there's no going back.