At first, I thought so too. But then I thought about it some more and I think I get it. I'm having a hard time putting it into words, but it seems to me that sexting is problematic because it can so easily be shared with anyone and everyone. If a 16 year old consents to sex, unless there are cameras, there's a reasonable expectation that there is privacy. It can stay behind closed doors. Sexting seems to open a person up to a lot of different kinds of vulnerability and exploitation. That picture can be reproduced and shared without your consent. Sexting also seems to cross over into pornography and the world of child pornography--which obviously the state has a compelling interest in eradicating. The state has a far-less compelling interest in regulating the sex lives of 16 year olds. That's why I think there's a difference in the ages for the two activities. I think it provides a level of protection for minors that's probably helpful. The law acknowledges that 16 year olds do consent to sex, but also acknowledges how easily exploited a 16 year old could be and affords some protection.
I have one question though--A lot of states might have an age of consent at 16, but there's also a clause about age gaps--for instance, it's still illegal if the other person is an adult of 4+ years etc. Is Georgia just straight-up 16 with any adult?
JMO