It would really depend on the circumstances. If the money is saved in the child's name (like, say, a trust), then it's the child's money when they turn 18 (or 21, depending on the state). As a parent, you can only recommend and encourage.
If it's actually the parents' money, then obviously, they have the say over how it's used. I would say, though, that you have to look at each child's individual strengths and choices. If you have a child who would be better served by becoming a plumber, say, instead of a doctor--that should be supported, IMHO. Trade school and/or seed money to start a business would be appropriate.
I guess I don't see the point in insisting the money be spent on college. if the child isn't college material (it happens!), then that's time and money wasted pursuing a degree that's not really wanted. Better to support that child in other ways--or possibly, not at all.