Why is it taken as a lot worse insult
 

To call someone a cunt rather than to call them a cock?

There is way more answer to that question than I think you're really interested in hearing.

I'll say that it has to do with the socialization of young men and women, and that it is categorically a worse insult to a man to be called a woman than it is to be called a negative word for a man. There are many studies on the nature of language as it applies to socialization, and the ones I'm familiar with largely conclude that the 'strong' words are associated with male traits, and the 'weak' with female.

This is the same reason that it is offensive to adolescent men to be called 'gay' or 'fags' or 'nancies' or 'sissies' because it implies they are less than men, e.g. women. Men are defined as "not women." Girls cry, so many would admonish their boys to not be "such a girl" or not to "cry like a girl." Similarly, if you're upset about something, you're "acting like a bitch", just like the (lesser) females do.

Archaic patriarchal values

I can see what you are saying - but it is also considered far more offensive to call a woman a cunt than to call a man a cock.

Because when you call a man a cock, you're just calling him a name. When you call a woman a cunt, socially speaking, you're relegating here to the status of an object: a pussy. Nothing else; just a hole to fuck and then babies come out. Given that that's -all- women have been in most societies for most of history, and they've spent the last 300 or so years clawing their way out of that situation, you can see how they'd take offense.

Because cock doesn't smell like a tuna can left out in the sun on a humid summer afternoon. Or so I've been told.

^^^ The lucky ones do, and are typically happy about it. :)

What's already been said is exactly what I was gonna say. It's okay to be called a boy but it's NOT okay to be called a girl. Calling someone a cock isn't even a thing, it's not an insult, it's just a word, and if you say it it sounds stupid and weird and makes the one who said it sound like the fool. Calling someone a cunt is a huge insult, and so many people can't stand the word. Vagina - Ultimite Feminine. That you dont want to be, apparently. You can call someone a pussy, cunt, vagina, ect, ect. It's all seen as an insult it doesn't come out "odd" or sounding weird. Call them a penis, cock, dick, the only one that rings is Dick. The rest, don't make sense.

SF, some of your confusion may be cultural. All of the people I know from the UK use (or used, rather) "cunt" way more casually. There is NOTHING casual about its usage in the US, and it therefore gets used very rarely if at all. It is never a term of sarcastic insulting endearment, and if you call someone your interested in "the prettiest cunt in the bar" (like one of my friends did a few weeks after he got to the US) you will very likely receive a similar drink-dumped-on-you response rather than any romantic advances.

In the UK "cunt" and "cuntie" are also pretty much the worst insults you can throw at someone also... although I does seem in America it is used less

The most profanity laced US rappers rarely use the word, whereas UK rappers will do (just as an example)

Yeah, they are used WAY less in the US...like, I swear like a sailor and hang with people who do the same and I've never used it ever, nor heard it used.

Ditto. The only person I've ever heard use it in conversation here in the States was my old boss at the pizza-joint I worked at in college. He was from Manchester, and he had a vocabulary of casual profanity that would curl R. Lee Ermey's toes. It rubbed off on the staff, but you should have seen the trouble we had the first few weeks! He'd toss off a "cunt" or "bitch" just in the course of taking the piss or making conversation, to say nothing of what he could be like when he got mad.

Contrariwise, I've never heard any American use "cunt" in conversation (unless they were hanging out with a Brit they knew well). It's the kind of thing that meant "Deadwood" had to go on HBO, and if used socially is likely to start a fight.

try "prick" instead of "cock." You'll see it's insulting.

"pussy" has a different slang meaning too.

It's possible to read way too much into these comparisons. It all depends on what you're juxtaposing.

"Cunt" is insulting? Interpretation of intent/intent itself must be what makes it so. If I understand the question's thrust, it's no more insulting, just more widely recognized as such.