I think this stems from the fact that new school are competing with schools who are already accredited. We have schools like ICO and PCO (Salus) that have been around for years. These schools naturally have an established curriculum and method of doing things. This is something new schools can't offer: accreditation, which cannot fully be given until the school graduates its first class, plus the first few classes are a learning process with curriculum and how things are run. Also, new schools need to fill spots because people tend to compete for spots at older schools. They have their benchmarks lower than usual because they need to fill these spots. Also, post graduation, when you name your school, many prefer to have a school that people are familiar with, kind of like a name brand.
On the other hand, the good things about new schools are that they can be more lax. They need their students to do well and graduate so they take a personal hand in their student's education. Also, all the materials used at new schools are brand new and state of the art.
There are pros and cons for both. I have been accepted to a new school and an old school. Making the decision is not easy.
Newer schools are:
KYCO (Kentucky College of Optometry): they just started taking applications in December I believe and plan on admitting their first class this fall
Western University of Health Sciences (California)
Midwestern University (Arizona)
University of the Incarnate Word Rosenberg School of Optometry (Texas)
MCPHS School of Optometry (Massachusetts)
These are just a few of the newer schools, I am probably missing a few.