I would never let 16 year old me vote.
25 is a solid voting age informed by life experience in the “real world” and a developed brain. Nobody in their late teens to mid 20s can vote with a grasp of reality and understanding of the actual problems that plague society. There is too much optimism and idealistic intentions at those ages. Progress is a slow march against an established defense. Progress, no matter the speed, gains more than attempting brute force attacks against a greater dying populous fervent in their position in opposition.
With a declining birth rate, slow and steady wins the race; or maybe Idiocracy was a documentary and WALL-E is a hopeful outcome of Surrogates.
That is the beautiful and tragic flaw of democracy and I wouldn’t have it any other way.