When I was in rehab we did it out of courtesy because there were others there with other struggles. It was nice to know 'why' they were there. Some are also family members of alcoholics.
For me, when I go to a meeting...it is a reconfirmation of my admittance to my addiction. I don't say it for others, just the same way as I don't go to meetings for others. If I help someone in my mission, then that strengthens me. But every time I say "Hi I'm Emerald and I'm an alcoholic", I'm reaffirming my reason for being there in the first place.
But you do what you feel comfortable with -no one is gonna kick you out because you don't want to 'say it'.