Kids are just like grown ups. Some do need more sleep than others. Our boy is an 8 hour sleeper per day. If he takes a nap he will be up around 3am or 4am for the day and not go back to sleep until around 9pm that night. He does not need as much sleep. However, my daughter and granddaughter are both 12 hour sleepers. The can both go to bed at 9am and if undisturbed will sleep until 10-noon the next morning. Some need more and some need less.
I honestly thing parents should "almost" still force kids to lay down and nap/rest during the day as long as possible.
In kindergarten they still lay down the first half of the year. If your kids are not used to that it is going to be very hard on them to lay there for an hour or so while the other kids still sleep. They start encouraging the kids to no nap after the winter break. Some kids will be booted from the class after lunch because they disrupt naptime for the rest of the class. That stinks for those who work and can't take off work to go pick up their school kids and take them to child care.
So, kids should stay with the nap routine until they are in kindergarten. Even if they don't sleep their bodies get rest. If they won't do it then lay down with them, read, watch some quiet style tv show or movie, spend time making up stories, talk, it is time not wasted.