Generally, people who are good at "book learning" have less practical knowledge, or common sense. Is this the fault of formal education? No. It's simply a difference in aptitudes. Common sense can be developed through real-world experience, just like book knowledge can be gained through formal education, and it's the individual's responsibility to develop both.
Formal education helps one learn basic facts of life for the most part, and it can help make eon's understanding of the world better. This can help one increase their common sense and make better decisions as a whole.
For the most part, common sense is really quite a different story from what one learns in school. It's the difference between street smarts and book smarts, and they're a horse of a different color from one another.
Formal education in and of it self doesn't impede common sense, but it also depends on the school district. If the school board is dominated by fundamentalist Christians who want to stick their hands into the science curriculum, then problems begin to arise and children begin to not get the education they need.
A formal education has nothing to do with common sense. There are many people whom are book smart, but lack common sense. However, education builds skills, and skill builds common sense. So the cycle could be an unending circle. A formal education is very important and it takes common sense to do well.
If anything, formal education enhances someone's abilities to use their common sense to explore and discover. In addition they can use their common sense to come to new conclusions using the information they obtain through their formal education. In order to do this though one must not simply memorize facts in their education but be taught to develop critical thinking.