Tired of playing dubs? Do they even play dubs?
I wish they did though, but in a best of 5 set match at the slams I can see them not wanting to take the risk of being on the court 5-6 hours per day for two matches. Heck, after some of the 5 hour matches that went on this year at the AO, imagine playing after that.
Of coarse this is the WTA board, so I should switch gears here... I do like seeing the women play dubs at all tournaments. They used to, and maybe that gets back to your question, tired of it? Davenport played dubs at the AO this year didn't she? Some of the women are on the court for hardly an hour sometimes in a singles match...