Why is the 'Strong silent type' both an enduring cliché of masculinity and also a farce?
I don't see it as an enduring archetype of masculinity or sexual attraction. My understanding is that sexual preferences have changed. An outgoing and extravert man with great sense of humor may appear to be more confident and sexually appealing to women. I may be wrong, but as a silent and serious type, this has been my observation.
I think that when it comes to what is coded "masculine," in a hard sense, and what is coded "feminine" in a soft sense, if we are to follow the notion of the hard/soft binary as presented in James Penner's Pinks, Pansies and Punks -- we might find that the trait of being loquacious is not considered masculine because it is considered a soft one. Someone who talks is often vulnerable and I think that's where the root of this stereotype comes from.
Men have been painted in media as and expected to be protectors and providers for at least the century of Freudian/Bernaysian advertising and we often forget that these are feminine qualities as well. Protection and provision are qualities that belong equally to mother and father/husband and wife/partner and partner. The act of talking, especially about feelings and problems, can and should belong to everyone who desires to speak about them. Personally, I love a talkative man. A distant, silent man is not the kind I want to come home to at night and wrap my arms around.