If I understand free agency correctly, some of those players are free agents simply because they only had a one-year contract to begin with. It doesn't mean their current teams aren't hoping and planning to have them back, just that the original contract expired and a new one hasn't been finalized yet. It will be interesting to see how many of them do end up returning, and how many take the opportunity to go elsewhere. There are certainly some impressive names on the list.
I think just about everyone was on a one year contract with an option (except the practice squad folks, who were outright free agents). So their clubs declined to pick up the option. You're right, it's not that they didn't want to sign the player, it's that they didn't want to re-sign the player at the current salary . . . that's what I'm assuming was going on with the Nat'l teamers anyway.
I still think the Freedom need to divorce themselves from their W-League past and make a run at Mitts, Lloyd or Osborne (if she's healthy). The talent level of this team is simply not as good as many others - losing Lori Lindsey is going to hurt. They don't have the talent to make up for losing their glue player (or, less tactfully, their brain).
I talked with Gabarra some months ago about offseason moves, and he said they tried really, really hard to sign Leslie Osborne but couldn't do it. Meanwhile, he doesn't seem to have a particularly good opinion of Carli Lloyd, and I think Heather Mitts was always headed to Philadelphia.