"It is + 形容詞 + to + 動詞" の構文 (3級必修)
It is important to ~ 〜は重要
It is necessary to ~ 〜は必要
It is difficult to ~ 〜は難しい
It is easy to ~ 〜は簡単
仮主語 It の代表構文。
important for vs to の使い分け
important for + 物事 ("important for your health")
important to + 人 ("important to me")
for は対象、to は主観。
"play an important role" = 重要な役割を果たす (英作文頻出表現)。
More importantly = より重要なことに (文頭の談話標識)。