Yes, redundancy helps in noisy environment. But this is only the tip of the iceberg, and the mistake here is to think human languages are "communication tools".

Yes, redundancy helps in noisy environment. But this is only the tip of the iceberg, and the mistake here is to think human languages are "communication tools". If they were, they could be easily simplified, replaced by better tools, etc. But languages are much more than "communication tools". For example, inside us, ideas have to mold themselves in a given human language framework. So do dreams, many parts of memories, etc. There is no "communication" here, if communication is transmission of information bewteen two or more agents. So, to take an extreme, if a language was much harder to learn but much more feature rich for non-communication purpose (e.g. a better language to dream in), it could very well be much better to choose the complex language over the simpler one, even if the learning part is harder.