そもそもfacebookが流行っていない

Android and Facebook haven't always gotten along but we've heard reports that they've set aside their differences and that an official Facebook App for Android was on the way. Though the Android Facebook App was going to be considerably different than the very popular iPhone Facebook App, we were absolutely positive that the Android Facebook App was going to take advantage of Android's unique features and deliver a worthwhile experience.

Images of Official Android Facebook App Leak

Android用のfacebookアプリケーションのリーク画像が掲載されています。
でも、日本ではそんなのよりmixi用のクライアントアプリでも開発したほうがいいと思うんですよね。