Deutsche Grammatik: die Ordnung des Kasuses

how is German grammar ridiculous:

dative noun comes before the accusative noun.
example: ich gebe meiner Schwester das Bonbon. (I give my sister the candy.)

however, when one of the nouns is replaced by its respective pronoun, the pronoun, regardless of its case, comes first.
example: ich gebe es meiner Schwester. (I give it (to) my sister.) or ich gebe ihr das Bonbon (I give her the candy).

if both nouns are replaced by their respective pronouns, accusative pronoun comes first.
example: ich gebe es ihr. (I give it (to) her.)

in love with German complicacy.