Also, if getting a tattoo is less annoying than wearing a bracelet you probably have some of them already and it can become even less clear.
In any case - where is the rash of young people with 'do not rescusitate' tattoos? Everyone I've seen that is supposed to have had one is a greyhair, well out of the young-and-dumb age. And even if you do 'later regret' the tatt and don't want to stump for tatt removal, just tatt a couple of lines through it or tatt something over it.
And then there's the young people who genuinely do not want to be rescusitated - what about them? Stigma enough carrying a medical bracelet amongst the young to begin with. I just don't see this supposed grey area of young people tattooing themselves with a mythical band name.
EDIT: To put it another way, this mythical youth tattooing himself errantly is such a vanishingly tiny fringe minority. Plenty of laws exist allowing for people to freely express themselves to death. The more stringent US states have a maximum blood alcohol content of .08 for drivers, which is higher than the level at which measurable cognitive effects occur on your co-ordination and attention. If we're really concerned about 'free expression' deaths, bring that number right down. There are tons of laws like it. There is no reason not to make it another social norm to say "tattoo 'do not resus' on your chest, and you won't be resuscitated". There's no need to pander to base idiots.