All booby traps abilities would be allot better designed if the explosion turned incendiary and the left DOT fire.
Delayed explosions (like Panzer Elite boobytraps in CoH1) would be another option. These would kill 1-2 squad members every second or so after a 2-3 second initial delay (with audio cue). Either way would give players time to react but still kill the entirety/majority of the squad if no action is taken. But then the price might have to be lowered as well.