A few reasons recreational divers are using our FFMs is that they offer benefits over a traditional half mask like :...
You forgot a big one:
I like a FFM since a loss of consciousness underwater is not an automatic drowning with (hopefully) a resuscitation at the end of it.
This might be worth considering for divers who may be concerned over a medical problem even though they can pass a diving physical. Divers using high PPO2 mixes to accelerate decompression are also candidates.