I'm going to have to do a bit of a post and run, as I'm working very long hours this weekend, but I'll try to get back to any replies, should any arise, around Tuesday/Wednesday time. So...
I think that it's true that there are certain things ingrained in society which can, in a very small and generalised way, contribute to a culture which views certain things in certain ways. For example - there are men out there who hold doors open for women. It's "manners" to do so, you see, and it's how men should behave. Or, for another example, the idea that you shouldn't hit women. Personally, I hold doors open for people, and I don't think you should hit anybody (with certain caveats allowing for unusual circumstances).
And I think there is a good argument to be made that both of the points of view above do contribute in a small way to a culture which can infantalise women. However, I don't think that it's any kind of direct, linear effect. The real world is far more messy and fuzzy round the edges than that. And I think that things such as that are far more symptomatic of attitudes within society than they are causal of such attitudes within society. And the relationship between the two need not be strong. We now live in a time which has become progressively more accepting of gay people. Yet we also live in a time in which kids at school use the word "gay" to indicate that something is worthless. You'd have thought the opposite would be true, were it more than a tenuous link between the two in either direction.
I, personally, don't like the use of the word "retarded" to describe people. It's not something I'm on a big crusade about, or anything, but I do think that it's common courtesy to not make a habit of using terms which are hurtful to people (be they part of some kind of minority or not). Which is kind of paradoxical to me as I do like edgy and near-the-knuckle humour and will sometimes laugh at something purely because I think it's an out-of-order thing to say. I also think that everybody will have a different threshold to everybody else when it comes to what they deem acceptable. I think most people would agree that someone taking offence at the word "niggardly" needs to receive a copy of a dictionary with a decent etymology section, rather than an apology.
But, specifically, I'd say that you shouldn't use the word "retard" or "retarded" unless you'll equally happily use the word "******" (or "Paki" or "Chink", or whatever offensive racial epithet describes an ethnic group you don't belong to) under the same circumstances. You may disagree.
And, my final tired and rambling thought for the day is that it's ironic that the two examples of negative traits in society were ones which pointed to and normalised the infantalisation of women, given that from what I've seen FtB, A+, Rebecca Watson, etc. thrive on the infantalisation of women.