The students have been there in the past. If you go back and look at the era of Frese, Welle, Taylor, etc., there was always a great student turnout. There have been years since where student attendance has been ok, but it's not been great in nearly 15 years now. If the program is winning, students show up more. It's literally as simple as that.
To say the crowd is in their 60s and 70s (not possessive) is an oversimplification of the drop-off in numbers over the years. There is still a wide age range going to the women's games from little kids to their parents, to 40- and 50-somethings to folks up into at least their 70s. The older set is the most likely to show up to every single game and be dedicated fans of the program. With on-the-court success, there will be more fans, regardless. If you think a recruit who wants to play in front of an actual crowd cares what the age of that crowd is, I think you're underestimating their motivation.