There are certainly different tasks for which different languages are suited, however for many tasks multiple languages are well-suited.

To paraphrase your question, you are essentially asking: "Why should I use language Y instead of X when X is fast enough for me, easier for me to read, and based on experience I like it better?" My immediate thought is that it sounds like language X is working quite well and aside from satisfying your personal curiosity there's no imperative to make that switch!