You could though probably make a wrapper that only kicks in when dd is called from the command line (as opposed to, say, from a script or some GUI program) and asking a confirmation "Do you really want to overwrite your main drive?", without breaking backward compatibility?

I have written a few wrappers like that on my own system preventing me from making a few common mistakes of mine (like scp'ing a file locally to a filename ressembling an IP address instead of on a remote server ;)