What the OP raises is an interesting question. I think the answer should probably be different depending on whether we are talking about Pro or amateur athletes. It's much easier to make an argument for Professional triathletes since the Olympic Committee has already pushed for gender parity in participation numbers.
A lot has been said already on this thread so I'm going to avoid repeating what has been said already.
One thing I do want to add is: how familiar are people with how slot allocation is actually made?
I'm saying this because the slot allocation over-represents women vs men in terms of percentage of slots over number of starters. In a way, you could say Ironman favours women by default in a way that happens to be dynamic (if more women participate, more slots go to women). The downside of this system is that it takes a big increase in participants to add a second slot.
Since very few races publish their slot allocation, I have created a spreadsheet that I use to calculate and estimate how many slots will go to each age group.
Here is a screenshot example of how slots may be allocated on a race with 40 slots and a small field of 1000 participants. The numbers of finishers I have manually collected from the live tracker of IM Tallinn (I can't tell how accurate this it). Although it may not be the typical race, I doubt the picture would change a lot if the same system is applied to bigger races. A bigger race is likely to have more slots distributed to older age groups and therefore less slots going to the massive AGs of M30,M35,M40,M45. I can share the spreadsheet if anyone would like to play with it and check my process/formulas.
In this particular example women would get 22% of the slots even though they are 11% of the participants. Statistically speaking, you are twice more likely to go to Kona if you are a woman.
I'm not sure what exactly could be done to have more women qualify without some arbitrary inflation for specific age groups (how do you choose which ones?).
Of course one option would be to cap at 1 slot per AG. What impact would it have on the average 30-50 man considering they probably represent the majority of IM customers? Nobody knows.
The only alternative system I could think of would be a system based on finish times similar to how qualification for the Boston Marathon is done. However, such a system would be highly arbitrary with so many variables impacting a long distance triathlon.
A different argument could be made about the "roll down" when a slot is rejected. Instead of a slot staying in the same age group until there are no takers, it could be treated as if it was an extra slot and therefore jump from one age group to the next.
Also, for many people going to Kona is a "bucket list" thing. You do it once and then never again. If a certain year sees a higher proportion of women going to Kona, could this potentially decrease Kona participation for the following year?
Finally, do women actually want more Kona slots? What problem are we trying to solve? Are there areas that could bring more benefits to women? How is gender parity among race organisers and decision makers in triathlon?