They were asked not to have a release date so that people don't camp out anymore.
Nope. Mall owners do not have to allow camping. It's private property. Just b/c Apple says product X will go on sale at 8am doesn't mean malls have to let customers in at 5am. But they do b/c it makes them $, especially when the the item goes on sale during pre-opening hours or off peak hours. Owners, of course, have to abide by local zoning ordinances, and that can limit camping, but that's a different matter.
1) Malls make a % of the gross of every store so it's in there interest to have shoppers shop at their mall. They aren't going to chase them away unless it's creating a dangerous environment. But as a mall cop told me when I picked up my iPhone 6, Apple campers are so much calmer than the limited edition shoe campers.
2) Camping draws in customers who then might buy something at another store while there. This could be something small like a pastry or bigger like a shirt that catches their eye in the display.
3) Apple is among the best non-anchor draws a mall can have. Apple doesn't have that many big releases that they are not going to tolerate a couple of major campouts each year.
Another poster here got the cigar -- Apple isn't being specific with the announcement because
Apple wants a "soft" release. The iPad is no longer a "hot" product like the iPhone based on many quarters of sales data. It's a good seller -- Apple's #2, but it doesn't excite passion. Even Mossberg is bored with the Air 2. Mossberg! Nothing would be more embarrassing for than to hold an Air 2 party and few came.