The biggest logic flaw is that if this is a boys line and only male figures sell, then why would you even have main characters be female in the cartoon? Disney/Lucasfilm can create whatever characters they want.
I assume the mission of Rebels is prime audiences for TFA, and appeal to younger kids (boys only?) that will bug their parents to buy them stuff.
So they get my 5-year old daughter all excited about the program, all excited about Sabine, and "release" (not really available) her well after the Christmas surge.
Sabine could have just as easily been a male character, or some androgynous alien, or a droid. But they chose to make her a young woman / old teenager, I assume to appeal to young girls and pull them in to the story and collecting.
If that is the case, make and release the damn figure straight out of the gates. Capitalize on your plan to pull in young girls. It also kills me I have to buy a Sabine t-shirt from Her Universe because Disney and others don't make one.
To me there is a lot of shared ownership on these oversights. Hasbro has missed the boat, and Lucasfilm/Disney licensing has missed the boat. I'm sure Disney could have strongly encouraged Hasbro to have Sabine (or Hera) be available at launch. Maybe they were too busy figuring out what new color of whiny fairy they could add to their Tinkerbell portfolio...