Jim,
As a resident of St. Louis for the first 36 years of my life, I agree with you that the weather in St. Louis, especially in late June - early July would be fine for a Women's Open. The weather was not a factor in the 1992 PGA, and the Seniors managed to handle the heat of the Senior Open in 2004. In addition, the LPGA, Champions Tour and Nationwide Tour each had very successful summer tour stops through the 1990s.
I also agree that St. Louis C.C. would be an excellent Women's Open site. Unfortunately, I think the lack of space for the non-golf facilities and the traffic logistics would be the primary problem (assuming for this discussion the membership was interested).
I attended the 2004 Women's Open at the Orchards in South Hadley, MA, and there were quite a few Corporate tents in addition to the merchandise tents and concessions. The Orchards appeared to have more space between holes for these facilities then does St. Louis. C.C.
St. Louis C.C. was scheduled to have a Women's Am in the mid-1980s. However, in post-Shoal Creek, St. Louis C.C. was likely not in compliance with USGA requirements per membership. The club opted out of hosting the tournament stating the turf was damaged and was not in proper condition to host that event. The rumors were that during the dates of the cancelled Women's Am, the course was in excellent condition.
From what I have heard and read, St. Louis C.C. membership diversity is adequate to host a USGA event. It would appear the club is no longer interested in hosting a USGA event, especially seeing that the boy's Junior Am is being held at Boone Valley next year. It is a shame that this great course, with a long USGA history is not interested in hosting a significant amateur event. This course would be a great location for any level of amateur play.