It is already a user option: If you want it, then use a client that does that for you. (I'm glad that the java chat clients allow me to disable this "command validation" feature.)

I don't think the HTML chatterbox will ever do this, even optionally. It is a long tradition and previous times it has been discussed there was much opposition to changing it.

I find it a very PMesque quirk that I appreciate even if newer members don't.