So you'd happily use the N' word, "fag," "gay," and similar since you can re-define them in your head to be just general insults, rather than associating negativity with the groups for which these words were originally used?

Sorry but we both know the reason you're using that word is because you want to paint them as being mentally handicapped which you perceive as "bad." You can pretend that isn't what you're doing but even if that is true that is how others perceive it, because when they hear the word "retard" they think mentally handicapped and you're using it as a derogative.