1. I agree, most women don't date up to reach a higher social class but for evolutionary reasons. See below what I mean with "date up".

2. I meant that the selection criteria are stronger nowadays than they used to be which means that the average health/attractiveness/intelligence of people in two-three generations will be higher than that of today. What this means is that the men/women who cannot find anyone to date them today is a sign that they probably shouldn't reproduce at all. The fact that people at the bottom would rather be single than dating someone unattractive is I believe, quite unique to our time.

3. I think we define hypergamy differently. Let's say that my definition also takes into account biological attributes, which isn't the classic definition, which normally only focuses on social classes.

But clearly you have interesting ideas, will be following.