If you can get a nicely-dimensioned hex trap, you probably don't need heat or much pressure to insert a nut, so they're nominally easier to use. Being smaller, they're easier to integrate into compact or complex designs. They're also more readily available, not a separate line item to procure on the BOM when there are other places you'll be using hex nuts anyway, and around 10% the unit cost.
Edited 1 time(s). Last edit at 07/02/2016 04:08PM by IMBoring25.