What if the BOff you lose isn't your Tasha? What if it's your Riker or your Data? Do you really want to have spent all the BOff points and all the time customizing their appearance and equipment to have them simply gone forever with no chance of getting them back?
I've had BOffs die. I've even had Captains die. I RPed their deaths, held their funerals and replaced them with new BOffs. But I planned it all. I chose the one that was to die. It wasn't some random quirk that cost me my favorite BOff.
I'd be for perma death of a BO, but there would have to be a really good reward for playing the mission. Also, you'd have to be made aware ahead of the mission that somebody is gonna not come back. Would spoil the surprise a bit, but people would just cry about it otherwise. Some sort of super rare BO would have to be the reward.
An alternative would be one of your BO's being taken by the borg. Then you'd do some missions to rescue them. When you do rescue them they have been assimilated, so now you get a borg BO back. Mission, would call for rescuing non BO's and getting some sort of different reward.
Just curious if I'm the only one that would like boffs to get killed and actually die? Like, maybe not all the time, but maybe a mission where one of your boffs actually dies and is gone forever? Straight up Tasha style. Could make for a dramatic episode thing. Or possibly create a 'real' mode where every time your boffs die they are actually dead and when YOU die (in a ground mission) your screen fades to black as you die but then you wake up with doctors working on you like part of a cut scene or something.
Just some food for thought to increase realism and immersion.