First, it is not a given that the person that wrote the library you cannot use would have written one that you can even if there was only one programming language. Something inspired them to write that library and your "good enough" default language choice may not have done it.
Second, competition results in tremendous redundancy I agree. However, it also seems to result in greater capability and greater accessibility as well. Which system produces better products: communism or capitalism? I think that history shows that capitalism utilizes resources far more effectively. We should always cheer greater competition.
Certainly it is annoying to have more choice than you want, especially if it means you have to make a bet on where to invest yourself (in terms of time and expertise). I do not agree though that we are somehow being held back by all these people writing great software in languages we have not yet chosen to use.