Historically, the window has always been extended to the prior year except for these recent World Championships.
And the current standards are still harder than ever with the short window.
I don't like the short window. I think the IAAF does it to promote fast early season races to the detriment of its athletes.
But I don't like the OP's or Letsrun's idea of a country that has three A athletes in total to send any three they choose, regardless of how fast they have run in the given period.
Go back and look at the recent US championships and see what that would have changed for team selection. Basically nothing since 2008.
And as soon as you have Rupp, Centro and Symmonds finishing 4th and losing a spot to someone who never even achieved a B standard, people will be whining about that.
And what other country would utilize this system?
Someone that had an injured A or B athlete and just wanted to send a filler.