It's worth remembering that since the dawn of time women's sexuality has been carefully controlled by patriarchal society. Women were made to feel ashamed of their sexuality and even 30 years ago there was a lot of moral and social control around the way women behaved sexually. Being a single mother was considered wrong because it demonstrated to the world that you had sex of your own accord without the ownership of a man and not only that but you went ahead and had a baby without male ownership - ie you took total control of your sexuality - a total undermining of patriarchal values. Having a baby while single is tough going but there is no reason why it was seen as an outrage other than the fact that it demonstrated that women didn't in fact have to be shackled to a man in order to procreate.
My mother was brought up (in Catholic Ireland, from 1955 onwards) with the very strongly instilled message that women are passive, worthless creatures who should wait for a man to select them. The idea that a woman would pursue a man or choose to have sex with him before he'd decided to marry her (note he had to decide to marry her) was abhorrent - women had no agency whatsoever. Once they got married, it was then her duty to give that man sex whenever she wanted, without contraception, so that she would have baby after baby after baby. There was no sense in any of this that women were even human, really. They were more breeding stock, objects of desire, useful vessels, maids, sex toys. That was soaked into every fibre of society.
Things were slightly different in the UK, I know, but not massively so. It was still a source of shame to be an unwed mother in the 80s. Women were still sent away to mothers' homes and their babies were still forcibly taken from them to be adopted by 'respectable' mothers (ie mothers who were owned by a man). It was legal to rape your wife in the UK up till 1991.
There is no mystery as to why consent is such a problem. Culture takes a long time to change and we are only now climbing out of 2,000+ years of culture that see women as possessions to be bought and sold. There are men alive today who grew up in a time when rape was so rarely prosecuted that, in conceptual legal terms, it couldn't be considered to an actual crime. Rape within marriage was entirely legal - once a woman signed the marriage register she signed over all rights to her body.
Women will still post threads on Mumsnet saying we should prevent 13 year olds from wearing short shorts because of 'the message it sends.' The underlying messages of thousands of years aren't going to die out in a few generations. But progress has been made, just not enough.
As for whether to teach consent, I can't see the harm. If nothing else it'll teach girls and women that they can say no whenever they want and no one has the right to override that, ever. Unfortunately there are far too many girls and women who don't know that - there are a shockingly large number of threads on MN from women who describe ongoing rape in a relationship and have no awareness of the fact that it is a crime.