Why don't the malls maximize their values by adding condos above and call centers within?

I wonder why the malls don't recognize the value of their real estate and get maximum value from it like Robinsons has and continues to do by building condos on top of the malls? Robinsons Manila built their condo's and hotel's right on top of the mall so all the residents make ready shoppers for their malls and supermarkets and cuch a convenience to the residents to have everything right in the same structure. And now Robinsons is taking it one step further by putting the call centers in the malls too. More customers again for their malls. Working, shopping, and sleeping all in the same complex such a great idea no more traffic!

Mall-based BPO facility in Robinsons Luisita
http://pinoybusiness.org/2009/09/21/mall-based-bpo-facility-in-robinsons-luisita/

Robinsons Place Residences are an integral component of the Robinsons Padre Faura Mall, one of Manila City's largest real estate developments and most comprehensive shopping, entertainment and mixed-use centers, presenting residents with a myriad of choices on their doorstep.

Robinsons Padre Faura Mall is one of the nicest Malls in Manila, with not just shops, department stores and supermarkets, but also such establishments as Star Bucks, TGI Fridays, McDonalds, Jollibee, Pizza Hut, Cinema complexes, and much more.

http://www.manila-condos.com/robinsons/index.htm

Also refer to this ideal location for a mini mall or supermarket
http://primerealestate.wordpress.com/