That doesn't work in situations where there is a power imbalance. For example, let's use our time machine and travel back to 1978. Consider the words "Nigger" and "Honky" in a presentation. Nigger was way more offensive, to the point that there really wasn't an equivalent slur you could apply to so-called white people.
It's the same thing with "bitch." There is a power imbalance such that there isn't an equivalent slur you can apply to men. "Bastard" doesn't even come close to capturing the degrading implications of "bitch" today. Maybe it did in the Middle Ages, but not today.
If you use general-audience television/movies and the speech of the young as an indicator, 'bitch' oddly seems to be becoming more acceptable over time. I'm not sure if this is a rise of sexism, or simply a weakening of the word's 'degrading implications'. (It might even be a indication of falling sexism; the word becoming less seen as a uniquely-gendered slur, and no worse than calling someone a 'dick' or 'pig'.)
A poll of usage and attitudes by age might be interesting.
On my ride to the office I had the thought that the launch of MTV may have something to do with it. Just as my parents' generation made "fuck" an everyday word, the MTV generation seem to have a different view of the words "nigger" and "bitch," possibly in part because of the glamorization of hip hop culture.
Perhaps, but also: quasi-feminist efforts to reclaim the word and imbue it with some positive qualities, of which a few examples would be:
• 'Bitch', Oakland- and then Portland-based feminist magazine, launched 1996
• Meredith Brooks' 2000 hit pop single, 'Bitch'
• a boomlet of books with 'Bitch' in the title, ranging from Elizabeth Wurtzel's 'Bitch: in Praise of Difficult Women' (1999) to Helena Andrews' 'Bitch is the New Black' this year
That is, I don't think it's just hip-hop or glamorization of misogyny that's the popularizing/de-taboo-ifying factor here.
The terms 'nigger' and 'honky' are inherently discriminatory because they are frequently used to describe membership of an entire group of people. They're not looking at individuals based on their own character, but judging them based on their group. These terms are occasionally used for individuals, but less commonly so.
'bitch' and 'bastard' are more commonly used for individuals, though they are occasionally applied to entire genders.
I agree with you about the power imbalance problem.
But to the extent that there is an equivalent slur toward men, I think it would be something like "dick" or "prick" rather than "bastard". Those are words that are derogatory in a gender-specific way, specifically directed at males.
It's the same thing with "bitch." There is a power imbalance such that there isn't an equivalent slur you can apply to men. "Bastard" doesn't even come close to capturing the degrading implications of "bitch" today. Maybe it did in the Middle Ages, but not today.