Because its the destination that makes the event worth going to for the casual fan. Camping out at a track for 4 days is fun for the hardcore fans, but those casual fans will not enjoy it especially if the weather is ...... all weekend. Look at the 3 locations in the USA for F1 (Miami, Vegas, and Austin) those are all cities that people regularly visit for weekend getaways, they are easy to travel to, and they can entertain a casual fan away from the track all weekend. By contract Indy was a very boring destination when you left the track.
