If the basic function of a community is to buy things and then go home, then I'd buy a condo/mall as an arcology. However, schools, museums and churches, libraries and sports arenas, and concert halls must exist, in order for a society to function healthily, happily, and rationally, so there are many more steps involved than at first blush. A mall-home would be like living in that giant ship in Wall-E. (We have a jogging track?) It would work for some but not well, and not for long.