Perhaps the best reason why you should remember the chemistry of molecules is the worldwide environmental pollution by synthetic molecules. According to the Wikipedia article about pesticides, "The term pesticide includes all of the following: bactericide, herbicide, insecticide, insect growth regulator, nematicide, termiticide, molluscicide, piscicide, avicide, rodenticide, predacide, insect repellent, animal repellent, antimicrobial, fungicide, disinfectant (antimicrobial), and sanitizer."
My gosh. We are surrounded by "icides". For articles about each of them, go to Wikipedia and search for the respective "icide" term. For example, a piscicide is a molecule that is poisonous to fish. Why on earth do we need piscicides?
Some of these "icide" molecules may be harmful to human beings and pets. For example, you need to wash fruits and vegetables before you consume them.