Well, I do think that's because αγαπάω (love) is a much stronger word than αρέσω (like). Το be honest, this structure is not something you'll come across too often in speech ("Αγαπάω/Λατρεύω την σοκολάτα" is probably more common.), but for teaching purposes, it's better not to mix different verbs up. ^.^
Even in generic statements, the article is needed when the verb (αγαπάω) is followed by a noun (I love children=Αγαπάω τα παιδιά).
Here, the second half of the sentence simply reads "I eat chocolate", which is the same in Greek, English, German and many more languages.