jIHo. is fine by itself for "I admire." as a full sentence, without an object.
But in the sentence "I admire Worf", there is a direct object for the verb: Worf is the one who "gets the admiring done to him".
In Klingon, verb prefixes specify not only the subject but also the direct object or lack of one.
jI- means that the subject is "I" and that there is no direct object.
So in this sentence, you need the prefix vI- which means that the subject is "I" and the object is third person (him, her, it, them).
Were you trying to say "wo'rIv luHo' Hoch"? That was my first thought upon seeing this sentence. :-)
Or would Hoch (with the meaning of "everyone") be treated as a singular subject rather than a plural one? English treats it as singular - "Everyone admireS Worf" - but Russian as plural: "Все восхищаються Уорфа." Meanwhile, German can express it both ways: "Jeder bewundert Worf," but also "Alle bewundern Worf."