I went to an outlaw game where nobody had any barrel bags or plugs. I asked the players why and their response was that they had safeties or turned their boards off. Needless to say, I never played with that group again.
It is fine to have a safety, but there should always be a backup/failsafe device that EVERYBODY can see at a glance to know that a given marker is truly safe from accidental discharge into someone's eyes. I'm with Axel. The other safety mechanisms are merely to avoid the accidental discharge into the real safety device.