Seeing the finalised list for Lexington makes me question this decision more, the Lexington draw isn't much (if any) stronger than Aldershot or Dublin with the highest rank being 251 and MDDA all the way down to almost WR500. A healthy Katie should be cruising through that field whereas they'd have to qualify and win a main draw match in Washington to beat the 75 points available in Kentucky
I think the decision to play Washington is simple. It's where Alex is. Since her time out, her perspective is to balance happiness off the court with her tennis career and not go chasing ranking points. I think they try to schedule to be together where there is an opportunity to do so. It does mean that after Washington, she's not likely to play before US Open qualifying, as like Wimbledon there is a dearth of opportunities for women in US Open qualifying to play in North America beyond the first week of August.