I'm waiting for a friend of mine to chime in, but she's doing a stage race this weekend. She has faced an extreme version of trying to find a field that makes sense for to race, with enough people in her range to make it worthwhile... definitely part of the Catch-22 that has been mentioned.
As rideaz has described, here in AZ there are usually two races; a massively combined race, and the P123. The P123 has some really fast riders. They truly kick ass. I'm sure moving to that race from the other one is a major "welcome to the big leagues" experience, as some of the women race the national circuit. One just won GC at Valley of Fire. She sometimes races the men's races, and can beat all but a few of the men when a RR course suits her. Personally, I want to see her, and all the women who want to get out there, have all the opportunities it's possible to present to them. Makes the whole racing scene feel... I dunno... healthier somehow. Just like having junior involvement. Some of those fields are also pretty small here in AZ.