Singapore airport has a great toystore in the main terminal (I bought quite a few toys when in Singapore a few years back)... which itself is marketed as a 24 hour shopping centre, for non-travelling people to come to for just for the shopping.
But you find those all-hours hub airports like Singapore and HK have all that shopping there for those people who may be spending several hours between connecting flights, but don't want to leave the airport. (HK airport's terminal 2 looks more like a shopping centre as well, with three toystores in the two terminals.)
The only problem with that though is that if you do too much shopping before a flight or between flights, you may not have the ability to take it on the flight (as you already have checked in your check-in luggage)... particularly if you like most people, are already taking on your limit of carry-on luggage to reduce or prevent having check-in luggage.