As a person in their 30's, I can tell you that the person I am now is radically different than who I was 10 years ago. I am infinitely more patient, and wiser than I was at 23, and I make much smarter decisions. I have also lived outside of academia in the "real world" for a long time, which I think will make the transition from school to private practice much less traumatic for me than for someone who has been going to school continuously since they were five. And there is no danger that I am going to school just because I can't imagine what else I am going to do after college, as I already have a successful career.
Please don't take this as me saying that all of you 20 somethings are immature. I am just saying that the person you are now will be very different from the person you are in your 30s. That's why the divorce rate for people getting married in their 20s is so much higher than those getting married in their 30s, because the person you will be is not completely formed yet at 20.
I know you won't believe me, but it's true. Ask your parents.
I would say though that being older is only really an advantage if you have used the extra time to become a better person and a potentially more successful vet. And I am sure that 95% percent of you kids will be just fine as vets. Though if I don't get in, I reserve the right to blame it "on those meddling kids"