I always thought of the Culture as the Federation, but super-hardcore. In the Culture, individuals can just upload their mind to a new, undamaged body if they're sufficiently injured that repair isn't an option. Even just popping the head off is enough to revive someone if they don't have a backup and can catch it in time. If the repairs will take a while, they can drop into a simulated reality to do something else while they wait. Some individuals get tired of living and decide to just end it -- no backup. Others get tired of living and have themselves warehoused until something interesting happens somewhere down the line.
But if they made Trek like that, I don't think 80's television audiences could have handled it. I'm not certain 21st century TV audiences are ready for that.