"One size fits all" doesn't work any better for education than it does for clothing or medical care. Standardization of curriculum just isn't a good idea when it comes to meeting the varying needs of students. There is some pretty interesting research on the different types of intelligence between people. Beyond academic intelligence, there is artistic intelligence, musical intelligence, and several other types. Too many public schools basically try to force fit students into an academic college track when they may have no desire (or ability) to go to college.

Vouchers would open up possibilities that are currently denied to most parents. The number of seats in private schools is limited in many areas (and nonexistant in others), but demand would drive supply. Within a couple years of a voucher program being implemented, you'll see several efforts to develop alternative schools to meet the local demand. Some of the more far out examples provided by voucher opponents (e.g. Moslem or Wicca schools) would be implemented only if there is local demand for them. It takes time and money to establish a school. No one would waste either time nor money if there wasn't demand for their product.

Vouchers would offer parents choice in their children's education. Choice is generally considered a good thing, don't you think.