Interesting - my daughters both took Calculus in high school and they spent a lot of time on limits prior to learning the rote mechanics of derivatives. I was surprised by that - after 30 years of practice using derivatives I'd sort of forgotten the basics and was pleasantly suprised to see how in-depth the curriculum at our high school is.

Having said that - the big problem is that in high school it's really hard to appreciate what good calculus is, whether you understand it or not. Once you're a practicing scientist or engineer it becomes obvious.