Generally, wikipedia is getting things right its success is proof of this. This holds true both for written content and to visuals. If you get the impression that many articles are still lacking visuals, you are likely correct. However, many articles also lack text, or are lacking in text quality. Wikipedia is not perfect and it is not complete this is a known fact to all (I hope). But it is continues to improve. It still needs more articles to be written, it still need many articles to be improved, it still needs many more images uploaded. But not the illustrations you propose.