If spamming and message quantity is the big problem for women I wonder why OKC doesn't just limit the number of first contacts or non-reply messaged a user can send out in any given time period. Add a notice to users encouraging them to use their first contacts wisely and to take their time in composing messages, you might see an improvement in messaging health.
One problem is that a huge number of people are simply terrible at expressing themselves via the written (or typed) word. Without wishing to flatter ourselves , the level of discourse experienced at HN is far higher than you will experience on the internet at large.
This leads to problems with both badly written, short and generic profiles (which makes writing well crafted clever messages to the person difficult) and people who find writing a message that really sells them as an ideal dating partner impossible. Not to mention that most people are uncomfortable writing about themselves in a personal way for a stranger.
I imagine the problems with rate limiting might be that users on a free site could well just sign up multiple accounts to get around this limit which would probably be yet more annoying.
