Broadcast camera lenses at the Olympics can cost as much as a Lamborghini

How is that working? Is it just their commentary footage? I would assume that the competition footage is all licensed from the same official source.

Not yet: http://www.hitachikokusai.com/Products/BroadcastandProfessio...

Mostly for legacy compatibility, but the lenses would need to be even larger to cover a larger sensor.

Smaller sensors mean bigger depth-of-field.

Shallow depth-of-field is incredibly distracting for video and difficult to work with. Everything is out of focus. It's mostly a photography/art thing to isolate your subject.

You can see how sports program would want everything to be in focus, instead of just one player. That would look ridiculous.