Don't feed the trolls.

I can't tell if you're admitting to being a troll, but if you are, I'm not holding this discussion for your benefit. What I do on this site is public, and I'm making this argument for the fraction of readers that will legitimately reconsider their opinions on whether or not to call some-one/thing a retard/retarded.

And in that way it is the same word as "stupid" or "idiot" or "crazy".

The word has lost its meaning. People who use retarded now use it as a general curse/insult, not as a word with definition.

I disagree wholeheartedly. Stupid, idiot, and crazy are all now far enough removed from their original definitions that they're acceptable to use as insults (see my comment about the euphemism treadmill); but retarded is most definitely not used as a "general curse/insult". It has a very specific meaning as an insult that is very specifically related to its definition as mentally handicapped. As an example, I didn't even consider calling you retarded because you told me I could curse, and not because I don't use the word retarded. That reason was superseded by another, more obvious reason: the common definition of retarded as mentally handicapped or something similar (which you'll find is still very much in use) doesn't fit what I was trying to say at all.

Not nearly as much as using the word nigger. In fact, AFAIK you'll get more a "why the heck are you using that word" reaction, so long as you aren't hostile in using the word.

Of course people won't be as offended, but they would still be offended. You might even find that they would be more confused than offended, but again, they would still be offended, which was my point.