tl;dr version of my standpoint:
lets stop pretending that the words 'pussy' and 'retard' have the same weight as the 'n word' or' fa***t'
I'm not gonna waste my time on a full-fledge essay about the ramifications of words people choose to use and how society reacts to it because I don't think it will change your opinion. The funny part about the overly sensitive PC youth is they are not interested in having a conversation. They want to stand on their soap box and condemn everyone else.
These words being deemed offensive is also largely a US thing. Not that it really matters, but it is interesting to point out