You won't really be able to hear the difference between sounds that you can't distinguish by pronouncing, so even if you don't feel like communicating, pronunciation is important. Pronunciation can also be a hint for remembering how a word is spelled.
発音し分けられない音はなかなか聞き分けられないから、コミュる気はなくても発音は重要だよ。あと発音はつづりを覚える手掛かりにもなるし。