To speak just your first muse: the more languages and ways of doing things you have learned, the better able to solve problems you are likely to be.

Different languages have different strengths and weaknesses and tend to encourage using different techniques for solving problems. For example, in Perl we often reach for a regex (in one of it's many guises) or a hash to get the job done. Those tools provide a completely different way of thinking about problems than languages like C++ where hashes and regexs are way down the list. However, having used Perl somewhat, I now have a slightly different approach to writing C++, and I really miss modifiers!

Bottom line: if you have the opportunity to learn a new language, do it - you will benefit from the effort.