Mega-Malls in Bangkok, like markets and especially night markets (the mall's distant ancestor), are centers of activity way beyond shopping. People hang out in them for this quality, as well as for their clean bathrooms, air conditioning, and extensive food courts. Teens show up in droves. Here's a sampling of some random stuff going on in malls:
yes they're ice skating
"beer gardens" with live music and art
and I'm no longer surprised to see Xmas trees all over malls (and everywhere else actually)
this one made out of straws...
MBK mall seems most related to its outdoor market ancestry...
Just like people in BKK, stuff overflows too...
Markets are a defining feature of Thai culture, and I guess these days a fair share takes place in malls. It's different from pure consumerism, and a bit hard to explain - come to BKK and see!