As a middle-school math teacher, I have seen many students who do understand abstract concepts, and even enjoy learning about things like Pi and the Pythagorean Theorem, but who appear to be unable to do so due to a weak grasp of math fundamentals.
Homeschool worksheets are a vital part of the student's homeschool experience. They allow the child to test his or her knowledge, and they offer them a practical application for their learning.
My students are engaged in the activity because they are always eager to find out what the next scene will be, and how the math problems will be nestled within. They also like how within each handout I inscribe the title in a way that fits with the theme of that particular scene - another attention catching technique. And since this review activity only takes about fifteen minutes of class time, it is quick yet extremely beneficial.
It is amazing the difference in effort you will get from worksheet to worksheet. Granted the amount of effort may vary immensely from year to year depending on the group of students you have.