The NCAA took over for the AIAW in 1982, the fall after I graduated. Title 9 took effect my first year of high school. Opportunities are greater now than they were then.
I don't think older women are getting faster. I certainly am not. I've been running since I was 15. My best times, for all distances, were when I was ages 24-28. I've run well since then, and didn't notice much of a drop off in my times until recently (I'm 47), but that may be partially due to injuries and a small weight gain.
I still place very well in local races, though, but it's not because I'm getting faster with age-- it's because the competition is weaker and there isn't much depth.
The younger women (locally) are not as fast as their predecessors were and the fields are not as deep as they were in the 80s.
On my post-collegiate xc team, 7 women could run a sub-5 minute mile and most of us ran 17:15 or faster for 5k and 35 or better in the 10k. The funny thing is that those times weren't that special and didn't make us seem "elite" or anything. Now, the local girls who run that time are considered super-fast. ;-)
In comparison to whom they are racing, they do seem fast, but it's only because there aren't many local girls running fast times.
I like placing in local races, but it IS kind of embarrassing that the younger women aren't racing better.