"Many women study the language."
Translation:Multae feminae linguae student.
It doesn't take the dative "as the direct object". It takes the dative because there is, in fact, no direct object, but rather an indirect object. "To dedicate oneself to" and "to be eager for" call for an indirect object, hence the dative case. Although, if you want to conceptualize it as being an irregular direct object that just takes the dative instead of the accusative, then I guess that doesn't exactly hurt. It still gets the job done. But... y'know... technicalities...