I'm going to disagree with your conclusion of why the women's standards are “easier” than the men's. I find your reasoning very faulted with considering that it is 32 minutes off WR . The only woman than has come within minutes of Radcliffe's WR is……Radcliffe. The same cannot be said of Tergat's record.
OK, what about comparing to the women's American record and the men's world record? Still a much bigger spread. Anyway, my point isn't that there aren't equal numbers of people faster than the standards but that the standards themselves are relatively easier than the best in the world, which they are by quite a bit. Just because the women's field is not as deep as the men's field yet doesn't mean that a time over 30 minutes slower than the women's world record is just as hard for women as a time only 17 minutes slower than the men's world record is for the men. It means we still have work to do before the women as a whole are as deep as the men.
So maybe the standard should keep tightening for the women based on my above paragraph that in the World there “are” more of a populous of men at WR range than women. It just seems like the US wants the trials even gender-wise and maybe it shouldn't be.
I believe the intention is actually to keep tightening the standard as the depth of the women's field continues to improve. I don't know if they are doing this to keep the numbers equal or if they have simply found that they want to get a field size of around 100-200 and set the women's standard to accomplish that, while the men's standard hasn't had to change to accomplish that (although, if the trend doesn't turn soon, they would have to loosen the standard to get a field of 100).
It is worth noting that at least the last two women's Olympic Trials have had more competitors than the corresponding men's Olympic Trials. If they were trying to keep the numbers even, it would seem that they aren't tightening the women's standard quickly enough.
As for what they should do, I can't offer an opinion. I do think a field size of 100-200 does make for a nice sized race. On a criterium course, having more could get problematic but it seems unnecessary to allow less in a road race where there is plenty of room for that many. Of course, in remembering that the whole purpose of the race is picking the Olympic team, the only necessity is that all who would have a chance to qualify are allowed into the race. The current standards are sure to accomplish that with quite a bit of time to spare.
BTW: The A standard gets you there for free, the B standard gets you in the race but you have to pay your way. Of course, if I were to run the B standard, I'd be more than happy to foot the bill.