German is a complicated language. Any speaker of e.g. French or Danish who has ever tried to learn German would agree to this. Coming from languages with only two genders and with no case outside the pronoun system, German, with three genders and with four cases throughout the nominal system, seems unjustifiably complicated, as if it had been specially designed to torment poor students. However, there is one area where German agreement morphology could not possibly be simpler, and where German is much easier for non-native speakers than e.g. French or Danish: predicative adjectives. Both gender and number distinctions, disappear when adjectives are used predicatively. This paper will try to account for why the Germanic languages that inflect attiributive adjectives but not predicative ones are all SOV-languages (e.g. German, Dutch, Frisian and Yiddish).
Sprachkontakt, Sprachvergleich, Sprachvariation: Festschrift Für Gottfried Kolde, 2001, p. 399-414