University students are emphatically not kids. The students who are US citizens are legal adults expected to vote an participate in democracy. At what age do you expect them to suddenly "grow up" and be responsible for their actions?
Being a functional adult takes practice. Nobody "grows up" until they've been responsible for their own actions for several years. Highschools (and to a lesser degree, parents) have largely passed the buck on this one.
If it were up to me people would get voting rights a few years after they get treated like an adult in all other capacities, I don't care if you move one up or move the other back.
Universities should treat students like adults but these people have no practice being adults so it's gonna be messy.