I just checked the 2015 WNBA all star roster - 9 of the speculative team were all stars with the other three being Fowles (didn't play the first half of the season), Taurasi (didn't play at all) and Stewart (college player.) Parker was also not an all star for the same reason as Sylvia and Diana. Of the centers on the all star team I don't think anyone would argue for either Dolson or Bone over Fowles and I think Lavender would also be a second choice.
A choice of Parker over Fowles is ignoring positional strengths and international players like Liz Cambage who is 6'8" 218 pounds - Sylvia is 6'6" 200, Griner is 6'9" 208, Charles is 6'4" 198, and Parker is 6'4" 175 - if for some reason USA needs low post defense (fouls or injury) Parker is not the answer so the issue was never about that comparison. This is not an unusual selection weighting for USA basketball - they carried Dolson and Lavender to the very end in 2014 waiting on word on Griner, they carried Jones in 2012 specifically to have a third option (which they definitely needed), they had Appel in 2010 as the third option. USA fears the low post and likes to carry three players in that position.
The players that most clearly fall into that tweener area are Catchings, EDD, Augustus, and Stewart. All of them shoot more than Parker and for higher percentages from the arc (which is very important in international competition as the men found out a few times), and Catchings is the only one to shoot a significantly lower overall percentage. And if you ranked them on defense, I suspect Parker would be at the bottom. Stewart obviously has the least experience but probably the highest upside.
Again - I am pretty shocked, and I probably would have traded Catchings for Parker straight up. I fully understand the post/power forward selections, I fully understand the guard rotation, and I am fine with Stewart being included. Augustus to me is a different player than the others and I think I understand her inclusion as well. To me it really comes down to Catch/EDD/CP and someone was going to scream about any one of those being left out. I think fans would probably scream least about Catchings being dropped, but I suspect the players might be most shocked by her being left out.